_s Party Polarization and
Legislative Gridlock
DAVID R. JONES, BARUCH
CITYUNIVERSITY
OFNEWYORK
COLLEGE,
This articleinvestigates
how partiesaffectlegislativegridlock-the
inabilityof governmentto enact significantproposalson the policy
accountssuggestthatdividedpartycontrolof govagenda.Conventional
ernmentcausessuch stalemate.I offeran alternative
partisanmodelof
gridlockthatincorporates
partypolarization,
partyseatdivision,andthe
interaction
betweenthesetwofactors.Usingan originaldataset of major
legislativeproposalsconsideredbetween1975 and 1994, I find that
and
dividedgovernment
doesnot affectgridlockoncepartypolarization
partyseatdivisionaretakenintoaccount.Instead,I findthathigherparty
increasesthelikelihoodof encountering
gridlockon a given
polarization
to theextent
but
that
the
of
this
increase
diminishes
proposal,
magnitude
andvetoes.
thata partyis closeto havingenoughseatsto thwartfilibusters
The persistence of divided party control of the legislative and executive
branches of governmentover most of the last three decades has prompted an
extensive,and as yet unresolved,debateabout whetheror not this phenomenon
leads to the stalematein the lawmakingprocesswhich is often referredto as gridlock. In the meantime,however,anotherphenomenon has been takingplace in
Americanpolitics that has receivedscant attentionin studies of legislativegridlock: the policy preferencesof the two partieshave become increasinglypolarized. Since 1990, more than half of all congressionalvotes have featureda majority of one party opposing a majority of the other party. This level of party
polarizationrepresentsa steadyincreaseover the 47 percentof such votes in the
1980s and 39 percentin the 1970s. To date, despite the indisputablerise in party
polarization,few scholarshave included a thoroughinvestigationof partypolarization in their studies of gridlock.
This articleexpands our understandingof legislativegridlockby examining
how partypolarization,in conjunctionwith varyingpartisanseat arrangements,
NOTE: The authoris gratefulto KathleenBawn,SarahBinder,MonikaMcDermott,BarbaraSinclair,
GeorgeTsebelis,anonymousreviewers,and the editorsof PoliticalResearchQuarterlyfortheir
commentson earlierversions of this article.
Vol. 54, No. 1 (March2001) pp. 125-141
PoliticalResearchQuarterly,
125
PoliticalResearch
Quarterly
affectsthe relativeinabilityof governmentto enact significantproposalson the
policy agenda. First, I briefly review the literatureon the divided government
hypothesisand discuss some aspectsof the theory that might explain the mixed
empiricalfindings.I then offeran alternativetheoryto explainhow partiesaffect
gridlock.This new theory focuses on partypolarization,and its interactionwith
partyseatdivision.I test these two hypotheses,using an originaldataset of major
legislativeproposalsconsideredbetween 1975 and 1998. The resultssuggestthat
partiesdo affectgridlock,but that their impact is more complex than the standarddivided governmentargumentsuggests.
GRIDLOCK
PARTISANMODELSOF LEGISLATIVE
The standardpartisanmodel thathas been offeredas an explanationfor legislative gridlock (or its counterpart,productivity)is the divided government
hypothesis (see Sundquist 1988; Cutler 1988; Kelly 1993; Cameron,Howell,
Adler,and Riemann1997; Edwards,Barrett,and Peake 1997). The divided governmenthypothesis claims that legislationis less likely to be enacted when the
President'spartydoes not hold a majorityof seats in both chambersof Congress.
Supportersof this hypothesisexplainthat the constitutionalseparationof powers
requirespolicy agreementamong the House, Senate,and Presidentin order for
bills to become law.They furtherarguethat agreementamong these threebodies
is likely to be thwartedduringdivided government(see also Kernell1991).
While the divided governmentargumentis quite intuitive, empiricalsupport has been mixed. For example,while Mayhew's(1991) systematicanalysisof
significantlaws passed in the postwar era finds no evidence that divided government is any less productivethan unified government,Kelly (1993) reexamines Mayhew'sdata using differentcriteriafor "significantlaws"and finds that
divided governmentdoes reduce enactmentof these laws. Takinginto account
the non-stationarynatureof time series data, Cameron,Howell, Adler,and Riemann (1997) find that divided governmentreduces enactment of "landmark"
legislation,but increasesenactmentof less significantlegislation.Edwards,Barrett, and Peake (1997) find that divided governmentincreasesfailureof legislation opposed by the President,but does not increasefailureof legislationthat the
Presidentsupports. Binder (1999) finds that divided government produces a
mild increasethe proportionof salient legislationthat fails, but has an effect no
greaterthan severalother causalvariables.
It is possible to explain the mixed empiricalevidence regardingthe legislative effect of divided governmentby re-examiningthree implicit assumptions
made in the divided governmentargument.First,the divided governmentargument implicitlyassumes that passagein Congressrequiressupport from only a
simple majorityin both chambers.Second, the argumentimplicitlyassumesthat
Congressand the Presidentmust agree in order to break gridlock. Third, the
argumentimplicitlyassumes that the two majorpartieshave distinctlydifferent
126
andLegislative
Gridlock
PartyPolarization
policy preferences.I shall illustratehow violationsof these assumptionscan lead
to breakdownsin the divided governmenthypothesis.
The argumentthatunifiedgovernmentis not prone to gridlockassumesthat
passagein Congressrequiressupportfromonly a simple majorityin both chambers. If this were true, then unified governmentwould guaranteethat the President'sparty had enough seats in Congressto pass its legislativeagenda. In the
Senate,however,a minorityof memberscan preventfinal action on a bill by filibustering(or credibly threateningto do so), and thereby prevent enactment.
Endinga filibusterrequiresthe supportof three-fifthsof the Senate,or 60 out of
100 votes. Therefore,unifiedgovernmentin which the Presidenthas the support
of less than three-fifthsof the Senatecould be just as proneto gridlockas divided
government.
Furthermore,the prediction that divided government leads to gridlock
assumes that Congressand the Presidentmust agreein orderto breakgridlock.
If this were true, then presidentialoppositionto legislationpassedby the majority party in Congress would prevent enactment during divided government.
However, the presidentialveto power is not absolute. Congress can override
presidentialvetoes with a two-thirdsvote in both chambers.Therefore,whenever
two-thirdsof the House and Senatesupport a bill, divided governmentwill not
necessarilylead to gridlock.
The prediction that divided government causes gridlock also implicitly
assumesthat the two majorpartieshave distinctlydifferentpolicy preferences.In
this article I use the term "partypolarization"to describe the degree to which
party preferencesare distinct from each other.1When party preferencesare
highly polarized,membersof one partyare more likely to be uniformlyopposed
by membersof the otherpartyon the policy matterat hand. Since the President's
partylacks a majorityin Congressduringdivided government,highly polarized
partieswould mean thatlegislationsupportedby the Presidentwould be unlikely
to musterthe majorityneeded to pass in Congress,and legislationthat passed in
Congresswould likely be opposed by the President,thus promptinga veto.
However,just because governmentis divided it does not necessarilyfollow
thatthe respectivepreferencesof the two partiesareclearlydistinct.In the American system of government,party preferencescan be highly polarizedin some
cases and have a considerabledegreeof overlapin other cases. When partypreferences are significantlyless polarized, members of one party may be no less
likely to vote for a measurethan membersof the other party are. In this case,
divided governmentwill not necessarilypreventagreementbetween the legislative and executivebranches.
1 In other words, polarizedpartiesare partieswhose respectivepolicy views would be distantfrom
each other if placed on an ideologicalscale. I do not seek to identify the particularsource(s) of
partypolarization,I am merelyinterestedin its effectson gridlock.
127
PoliticalResearch
Quarterly
Overall, the argumentthat divided party control of governmentleads to
gridlockis premisedon assumptionsof majorityrule, absoluteveto, and distinct
parties.By takinginto accountthe importanceof the filibuster,veto override,and
variationin partypolarization,I shall attemptto constructan improvedmodel of
how partiesaffectlegislativegridlock.
The divided governmentargumentassumesthat supportfromthe President
and a simple majorityin the House and Senateare necessaryand sufficientconditions for enactinga law.As a result of the filibuster,however,legislationsupportedby the Presidentneeds not only simple majoritysupportin the House, but
also three-fifthssupport in the Senateto overcomegridlock.As a result of veto
overrideprovisions,legislationopposed by the Presidentcan, in fact, overcome
gridlockif it has two-thirdssupportin the Senateand in the House. Overall,in
orderforlegislationto overcomegridlockthe Senatealwaysneeds to have at least
three-fifthssupport and sometimes as much as two-thirds, while the House
alwaysneeds to have simple majoritysupport, and sometimes as much as twothirds. Recent works by Jones (1995) Krehbiel(1998) and Bradyand Volden
models focusing on the
(1998) formalizethis argumentthat supermajoritarian
Senatefilibusterand the veto are more appropriateto the study of gridlockthan
majoritarianmodels (such as the divided government hypothesis). However,
institutionsare generally
these gridlockmodels that focus on supermajoritarian
have
to
and
thus
little
(or
test)
models,
say
regardinghow various
nonpartisan
more
or
make
less likely (other than
of
conditions
gridlock
types partisan
might
to suggest that divided governmentis irrelevant).
Given that not only majoritysupport, but often supermajoritysupport is
needed to breakgridlock,what partyvariablesaffectthe likelihoodof achieving
largemajoritiesin eachchamber?One factoris the levelof partypolarizationin each
chamber.When partypolarizationis low, Democratsarenot uniformlyopposedto
Republicanproposals,and Republicansare not uniformlyopposed to Democratic
proposals.Withthe possibilityof votes fromboth parties,largermajoritiesaremore
likely,and thereforegridlockshouldbe less likely(see also Binder1999).
At the same time, however,while low partypolarizationshould reduce the
likelihood of gridlock,higher partypolarizationmay not uniformlyincreasethe
likelihood of gridlock. Instead, the effect of higher party polarizationmay be
dependenton a second partyvariablein each chamber:partyseat division.In the
Senate, when neither party is close to having a filibuster-proofor veto-proof
majorityhighly polarizedpartiesshould be most likely to cause gridlock.This is
because neitherpartyhas enough seats to preventa filibusteror overridea veto
if the otherpartysolidly opposes its agenda,and partypolarizationincreasesthe
oppositionof one party'smembershipto the otherparty'smembership.2However,
2 Any group of 41 or more like-mindedSenatorscan filibuster.In this sense, low partypolarization
is no guaranteeof relief from the threat of filibusters.On the other hand, however, high party
128
andLegislative
Gridlock
PartyPolarization
as a party comes closer and closer to a filibuster-proofand veto-proofmajority
(such as a three-fifthsmajorityalongwith controlof the Presidency),partypolarization should become less and less likely to increase gridlock. This happens
because as a partygets closer to the supermajorityof seats it needs to enact its
agenda,it needs fewervotes frommembersof the other party.Therefore,higher
party polarizationis less of an obstacle to the supermajoritysupport that is
needed to breakgridlock. In other words, as a partygets closer to a veto-proof
and filibuster-proofmajorityin the Senate,partypolarizationprovidesa diminishing marginalboost to legislativeobstruction.
Partyseat division should have a similareffectin the House. When the President'spartydoes not have a majorityand the opposition partydoes not have a
veto-proofmajority,highly polarizedpartiesshould be most likely to cause gridlock. This is because neitherpartyhas enough seats to enact its agendawithout
help from the other party However,as the President'spartyapproachesmajority
partystatusin the House (or, less likely,the opposition partyapproachesa vetoproofmajority)partypolarizationshould become less likely to increasegridlock.
In these cases, a partyneeds less help fromacrossthe aisle to pass its agenda.In
sum, as a partyapproachesthe majorityit needs to pass its agendain the House
without fearof a veto, partypolarizationprovidesa diminishingmarginalboost
to legislativeobstruction.
Overall,reanalyzingthe assumptionsof the divided governmenthypothesis
suggestsa new, more nuancedhypothesisregardingthe effect of partieson gridlock. This new hypothesis,which I will referto as the partypolarizationhypothesis, arguesthat unified versus divided governmentper se does not affectgridlock. Instead, gridlock is caused by the interaction between two partisan
variables:party polarizationand party seat division. While a few scholarshave
looked at one or the other of these variables,none has analyzedthe interaction
between them that is central to this hypothesis. Binder (1999) examines the
effect of partypolarizationon gridlock,but does not take into accountvariation
in party seat division. She thereforedoes not test whether the effect of party
polarizationdiminishesunder certainpartisanseat configurations(as the discussion abovewould suggest).In fact, Bindersuggeststhat divided governmentwill
still have an effecton gridlockeven when partypolarizationis takeninto account
-an assertionthatis contraryto my hypothesis.Coleman(1999) looks at Senate
supermajorities,but only as a dichotomousvariable,and without consideringits
interactionwith partypolarization.3
polarization-in which membersof one partyuniformlyoppose membersof the other party-will
necessarilyincreasethe threatof filibusterswhen neitherpartyhas a filibuster-proofmajority
3 Coleman does consider possible effects of divisions within each congressionalparty,but not
directlybetween parties,and not in interactionwith partyseat division.
129
PoliticalResearch
Quarterly
In contrastto previousworks, this study arguesthat higher partypolarization increasesgridlock,but that the magnitudeof this increasediminishesto the
extentthata partyis close to havingenough seats to thwartfilibustersand vetoes.
Therefore,unifiedgovernmentis just as proneto gridlockas dividedgovernment
when parties are highly polarizedand neither party has a large majority.Conversely,divided governmentis just as productiveas unified governmentwhen
party polarizationis low or when one party has a veto-proof, filibuster-proof
majority.
DATA AND METHOD
This articleexamineshow differentpartisanconfigurationsaffectthe relative
inability of government to enact significant proposals on the policy agenda
("gridlock").Given this goal, the first step in the analysis is to identify what
Mayhew(1991: 35-36) refersto as the "agendaof potential enactments."Once
this agendais identified,it is then possible to comparethe conditionsassociated
with governmentalfailurerelativeto those associatedwith governmentalsuccess,
for each item on the policy agenda.
Kingdon(1984: 3) defines the agendaas "thelist of subjectsor problemsto
which governmentalofficials,and people outside governmentclosely associated
with those officials,are payingsome serious attentionat any given time."I idenQuarterlyWeekly
tify such significantpotential enactmentsusing Congressional
lists of majorlegislativeproposalsfor every Congressfrom 1975 through
Report's
1998 (94th-105th Congress).The startingdate of 1975 is used becausethis is the
firstyear that the three-fifthscloturerule for ending filibusterswent into effect.4
For each Congress, I examined every issue of Congressional
QuarterlyWeekly
Reportthat was published duringits two-yearterm. Using every periodic list of
major legislativeproposals contained in these issues, I compiled one comprehensivelist for each Congress.FollowingMayhew(1991: 40), I exclude fromthis
data set a small number of proposalsthat would not constitute "law"if passed,
includingpresidentialappointmentsand non-bindingcongressionalresolutions.
I also exclude treaties,which do not requirepassagein both chambers.
The smallest possible unit of analysisfor gridlock is the failureof a single
item on the policy agenda.Specifically,gridlockcan be said to occur whenevera
4 From 1917 until 1975 the Senateoperatedunder a two-thirdscloturerule. With a two-thirdscloture rule, the theorywould predicta slightlydifferentrelationshipbetween partypolarization,seat
share and gridlock.For example,with the two-thirdscloture rule (priorto 1975) partypolarization in the Senatewould be expectedto producegridlockeven when a partyheld between 60 and
66 percentof Senateseats. With the currentthree-fifthscloturerule, partypolarizationis not necessarilyexpected to increasegridlock in this seat range. For purposes of brevity and clarity,this
work does not attemptto elaborateand test the differentimplicationsof the theoryunder different
cloturelevels.
130
andLegislative
Gridlock
PartyPolarization
significantproposal on the policy agenda fails to be enacted into law during a
two-yearCongress.Using this definition, I create a dichotomous gridlockvariable. Thisvariableis coded 1 for proposalsin the dataset that failedto be enacted
into law-regardless of what stage in the legislativeprocess the proposaldiedand 0 for proposalsthatwere enactedinto law-regardless of the particularroute
to enactment.5
For each case in the dependent variable,we need a measurementof party
polarizationand a measureof partyseat division in each chamber.Partypolarizationvariesnot only acrossCongresses,but also acrossmajorpolicy initiatives
within a given Congress.In the 105th Congress,for example, the partiesheld
widely divergentviews from each other on the subject of managedhealth care,
but held positions that were more difficultto distinguish from one another on
the subject of transportationfunds. This study arguesthat even within a Congress, policies on which the partieshave similarpreferencesshould be less likely
to become mired in gridlock than policies on which the partiespreferencesare
far apart.Therefore,measuresof partypolarizationthat are aggregatedby Congress are inappropriatefor testing the hypothesisat this level (and can even lead
to counterfactualinferences;see King 1997). Since only individual-levelanalysis
can effectivelybe used to explain variationsin gridlock across policy items as
well as acrossCongresses,I measurepartypolarizationon a case-by-casebasis as
the absolutedifferencebetween the percentageof Democratsvoting yea and the
percentageof Republicansvoting yea on a measure.6
Ideally,the votes used to measurepartypolarizationshould attemptto capture the sincere preferencesof membersratherthan any strategicbehavior.For
this reason,I measurepartypolarizationon the finalrecordedvote takenon each
measure in each chamber. Though other votes, such as those on particular
amendments,may sometimes display higher party polarization,final votes are
the most conducive to sincere voting on the issue at hand. As Mayhew(1991:
120) aptly points out, final votes "arethe ones that pose an up-or-downchoice
between passing a bill or doing nothing .... Victoriousamendmentsare incorporatedin the final measures;others are left behind."7While measuringparty
polarizationon a case-by-casebasis is the best way to establish a direct causal
link and avoid inferenceproblemsinherent in aggregateanalyses,it does carry
a caveat. Since party polarization is measured using votes on each proposal,
5 The data set contains49 cases of gridlockand 181 enactments.
Ideally,the measureof partypolarizationshould capturethe degreeof distancebetweenthe parties.
While it is difficultto measurepartydistanceat the individuallevel, the index of partydifference
measureprovidesa good approximation.When aggregatedby Congress,the index of partydifference correlateswith the distancein partymedians (based on DW-NOMINATE
scores, a common
measureof memberideology)at .91 (Senate)and .87 (House) for the periodunder consideration.
7 In the data set, polarizationrangesfrom 0-97 (House) and 0-100 (Senate),with means of 33 (H)
and 29 (S), and standarddeviationsof 26 (H) and 28 (S).
6
131
PoliticalResearchQuarterly
significantproposalsthat did not receiverecordedvotes arenecessarilyexcluded
from the analysis.However,analysisof these excluded cases suggests that their
exclusion does not bias the findingsof this study8
For party seat division, I measure the percentageof seats held by voting
membersof the President'spartyin a chamberat the time each proposalwas considered.In the Senate,since the President'spartyonly needs a three-fifthsmajority to end a filibusterwhile the non-presidentialpartyneeds a two-thirdsmajority to overridea veto, it is much more likely that largerproportionsof seats held
by the President'spartywill help overcomegridlockthan it is that largerproportions of seats held by the non-presidentialparty will help overcome gridlock.
This is also the case in the House, where the President'spartyneeds only a simple
majorityfor passagewhile the non-presidentialpartyneeds a two-thirdsmajority to overridea veto.9
Finally,to test the divided governmenthypothesis, I code for unified versus
dividedgovernment.10
Since the divided governmenthypothesisclaimsthat only
unified party control of all three legislative actors-House, Senate, and President-can break gridlock,proposalsthat were consideredwhen the President's
partyheld a majorityin both the House and the Senateare coded 0 for unified
government(N = 58) and proposalsthat were consideredwhen the President's
partydid not hold a majorityof seats in both the House and Senateare coded 1
for divided government(N = 172).11
8
Approximatelytwo-thirds of all proposals listed in CQ received recorded floor votes in both
chambers.Using Poole and Rosenthal's(1997) coding scheme of 99 specific issues, I find that all
of the issue areascoveredby the excluded cases are also presentamong the included cases. I also
develop a rough estimate of party polarizationfor most (86 percent) of the excluded cases. A
Chow test suggests if these cases were included they would have no significantimpact on the
magnitudeor significanceof any of the key coefficients.
9 Presidentialpartyseat percentagerangesfrom 32-69 (House) and 37-61 (Senate),with means of
47 (H) and 49 (S), and standarddeviationsof 10 (H) and 7 (S).
10 While other variablessuch as leadershipinvolvementand presidentialposition are also relatedto
legislativeoutcomes, they are generallymodeled as having an indirectimpact via the preferences
of partymembersin Congress-a factorthat is alreadyaccounted for in the analysis.For example, Bondand Fleisher(2000) find thatwhen a Presidenttakesa position on a measurehe is more
likely to draw more support from his own partythan from the opposition party,and when congressionalleaderssupport such measures,fellow partisansare more likely to support them and
opposing partymembersare more likely to oppose them (thus affectingpartypolarization).I this
study,I restrictmy focus to the effectsof polarizationratherthan its potentialcauses.
11 Consistentwith the divided governmenthypothesis, the 97th-99th Congressesin which Republicans held the White House and a majorityin the Senate,but not a majorityin the House, are
coded as divided government.There is no significantdifferencein the results if two separate
divided governmentdummy variablesare used instead (one for 97th-99th, another for "pure"
divided government),indicatingthat the findings are in no way dependent on whether divided
governmentis defined broadlyor narrowly(resultsavailablefrom the author).
132
andLegislative
Gridlock
PartyPolarization
Since the dependentvariablein this study is dichotomous(a proposaleither
fails or is enacted into law), I employ logistic regressionanalysis.The analysis
thereforeevaluatesthe impact of the independentvariableson the likelihoodthat
willfail to enacta givensignificantproposal("likelihoodof gridlock").
government
FINDINGS
Table1 presentsthe resultsof five logistic regressionmodels testingalternative partisanexplanationsfor gridlock.'2The first model estimatesthe effect of
divided governmentalone on the likelihood of gridlock. As predicted by the
divided governmenthypothesis, the coefficientfor divided governmentis positive and significant.The specific effect of an independentvariablein a logistic
regressionmodel can be interpretedby translatingthe resultsinto probabilities.
In this case, the results indicate that the presence of divided government
increasesthe probabilityof gridlockby 12 percentagepoints-a fairlysubstantial amount.However,the divided governmentvariabledoes not actuallylead to
any more cases being correctlypredicted.
The next column in Table1 tests the relativestrengthof the partypolarization hypothesis versus the divided governmenthypothesis by adding variables
measuringpartypolarizationand the interactionof partypolarizationwith presidentialpartyseat percentagein each chamber.The partypolarizationhypothesis predicts that higher party polarizationin a chamberincreasessystem-wide
gridlock,but that the magnitudeof this increasediminishesto the extent that the
President'spartyhas a largerpercentageof seats in that chamber.If this hypothesis is correct,the coefficientsfor partypolarizationshould be positive and the
coefficientsfor the interactivetermsshould be negative.
The results of the estimation of model 2 support the party polarization
hypothesis.In both the House and Senate,the coefficientsfor partypolarization
and for partypolarization'sinteractionwith presidentialpartyseat percentageare
in the expecteddirection,and in the Senateboth variablesare statisticallysignificant. Furthermore,inclusion of the partypolarizationhypothesisvariablesprovides a statisticallysignificantboost in the model chi-squareand improves its
predictiveefficiency On the other hand, the resultssuggest that divided government does not have any impact on gridlock over and above the effect of party
polarizationand its interactionwith partyseat division. When these other party
variablesare included in the estimation,the magnitudeof the divided government coefficientdrops and its significancevanishes.
It is worth speculatingwhy,empirically,the partypolarizationand partyseat
division in the Senateseem to have a more significantimpact on gridlockthan
12 I also ran the model with
dummy variablesfor each Congressto test for any Congress-specific
fixed effects.The fixed effectswere neitherjointly nor individuallysignificant,while my key variables remainedjointly significantand their signs and magnitudeswere not affected.
133
PoliticalResearchQuarterly
1
TABLE
OFPARTY
EFFECT
VARIABLES
ONGRIDLOCK,
1975-1998
IndependentVariables Model 1
Divided government
.8560**
(.4404)
Model 2
.4347
(1.0402)
Model 3
.2390
(.7294)
Model 4
Model 5
.4945
(1.0037)
Partypolarization
(Senate)
.1028**
(.0584)
.1372***
(.0446)
.1568**
(.0671)
.1449***
(.0322)
PartypolarizationX
seats of President's
party(Senate)
-.0016*
(.0012)
-.0018**
(.0009)
-.0021**
(.0012)
-.0020***
(.0006)
Partypolarization
(House)
.0453
(.0511)
PartypolarizationX
seats of President's
party(House)
PartypolarizationX
divided government
Constant
-.0002
(.0011)
Numberof cases
Initial-2 log
likelihood
Model chi-square
Reductionin error
Aldrich-Nelsona
pseudo-R2
-.0087
(.0220)
-1.9859*** -4.0828*** -3.2619*** -3.4660*** -3.0646***
(.7175)
(.9200)
(.3656)
(.4031)
(.9960)
230
230
230
230
230
238.262
238.262
238.262
238.262
238.262
70.786*** 70.945*** 68.909***
4.325**
78.443***
30.63%
32.63%
26.53%
30.63%
0.00%
.04
.51
.47
.47
.46
errorsin parentheses).
coefficients
Note:Entriesareunstandardized
(standard
*p < .10, **p< .05,
***p< .001 one-tailed.
aUses Hagle and Mitchell(1992) correction.
similarmeasuresin the House when both are includedin the model. One possibilityis thatwhen partisanconditionsin the Senatearesufficientto overcomethe
institutionalobstaclesto enactmentin thatchamber,they are empiricallylikely to
be sufficientin the House as well, but the reverseis not necessarilytrue. In this
case,variablesmeasuredin the Senatewould be sufficientfor explainingalmostall
of the partypolarizationeffectin both chambers.This scenariois consistentwith
the empiricalfinding that partyvariablesare highly correlatedacross chambers
(polarization.78, seats .87), and the factthatonly the Senateallowsfilibusters.'3
do not mean to suggest that passageof a proposalin the Senateguaranteesenactment.What I
do suggest is if partypolarizationin the Senateis low enough to overcomea potential filibuster
13 I
134
Gridlock
andLegislative
PartyPolarization
Since the insignificanceof the divided governmentvariablecould be attributable to mispecificationof the model, I estimate two alternativemodels with
divided government.First, model 3 removes the insignificantHouse variables.
Nevertheless,dividedgovernmentremainsinsignificant-unlike the partypolarization variablesfrom the Senate. Second, model 4 tests for the possibility that
divided governmentis significantonly when partiesare polarizedby adding an
interactionbetweenthese two variables(using Senatepolarization).However,the
originalpartypolarizationhypothesisoutperformseven this reviseddivided governmenthypothesis.
Finally,I estimate a reduced model of policy gridlock that includes only
partypolarizationand its interactionwith presidentialpartyseats in the Senate.
As in the previous three models, these two variablesare significantand retain
their relativemagnitude.Furthermore,removalof the divided governmentvariable does little to diminish the explanatorypower of the model.14
Figure1 translatesthe resultsof this estimationinto probabilisticterms.The
figuredisplays three lines, each representingthe effect of party polarizationon
gridlockfor a differenthypotheticalpercentageof Senateseats held by the President'sparty:41 percent,51 percent,and 61 percent.When partypolarizationis
non-existent (0 percent), the probabilityof gridlock for all three seat levels is
equally unlikely-about .04. However,as party polarizationrises, the effect on
gridlockis differentfor each of the threeseat levels. For the line labeled41 percent, greaterlevels of partypolarizationdramaticallyincreasethe probabilityof
gridlock,as indicatedby the steep, positive slope. Specifically,gridlockbecomes
more likely than enactment(probability> .5) for all levels of partypolarization
above 48 percent.When the President'spartyhas a largerproportionof Senate
seats-the line labeled51 percent,for example-party polarizationstill increases
gridlock,but the magnitudeof its effectdiminishessomewhat.In this case, gridlock becomes more likely than enactmentonly for levels of party polarization
above 71 percent. Finally,when the President'sparty has 61 percent of Senate
seats, gridlock is always less likely than enactment (probabilityalways < .5),
regardlessof the level of partypolarization.
14
(in conjunctionwith a particularpartyseat division),a similarlevel of partypolarizationand seat
distributionin the House (as expected empirically)should be more than sufficientto achieve the
simple majoritysupport that is needed for passagethere. But, if partypolarizationin the House
is just barelylow enough to ensuresimple majoritysupportin the lower chamber(in conjunction
with a particularpartyseat division), it is quite possible that a similarlevel of partypolarization
and seat distributionin the Senatewill not be sufficientto overcomepotential filibustersin the
upper chamber.
While individualbill-level analysisis the most appropriatemethod for testing the partypolarization model, the results are similarwhen one conducts an aggregateanalysisof the model using
Mayhew'sdata on the number of enactmentsper Congressand averagepartypolarizationscores
for each Congress(Jones 1998).
135
PoliticalResearchQuarterly
1
FIGURE
AND PARTYSEATDIVISION
ESTIMATED
EFFECTOF PARTYPOLARIZATION
ON THEPROBABILITY
OF GRIDLOCK
(BASEDON TABLE1, EQUATION5)
0.90.8 -
0.7
r
I
I
- 0.6-
))
| 0.45
0.4
0.3 0.
c .r
0.2
0.1 Le L
0
5
10
c,
15
c
c c
cc F
.C'?-(?
20
'"
rrr c
,?
- ?'
,,
25
30
_
_ _____
------
35
40
45 50 55 60
Polarization
Party
(%)
65
70
75
80
85
90
95
100
41% of seats held by President'sparty
51% of seats held by President'sparty
61% of seats held by President'sparty
Figure 1 also offersan explanationwhy divided governmentmight appear
increase
to
gridlock when one does not control for party polarizationor party
seat division. The regressionline representinga 41 percentminorityof seats for
the President'spartyis necessarilyan exampleof divided government,while the
line representinga 51 percentmajorityof seats for the President'spartyis more
typicalof unified government.5In otherwords, divided governmentmay appear
more prone to gridlocksimplybecausepartypolarizationis moreharmfulto legislationwhen the President'spartyhas fewerseats, not becauselegislative-executive agreementis precluded.
CONCLUSION
Basedon originalindividual-leveldata from 1975 through 1998, this article
finds thatdividedgovernmentper se does not causegridlock.Instead,the results
15
Though this could also qualifyas a form of divided governmentif the President'sparty did not
have a majorityof House seats.
136
andLegislative
Gridlock
PartyPolarization
show that higherpartypolarizationincreasesgridlock,but that the magnitudeof
this increasediminishesto the extent thata partyis closer to havingenough seats
to thwartfilibustersand vetoes. Therefore,unified governmentis just as prone to
gridlock as divided governmentwhen parties are highly polarized and neither
partyhas a largemajority.On the otherhand, divided governmentis just as productive as unifiedgovernmentwhen partypolarizationis low or when one party
has a veto-proof,filibuster-proofmajority.
Based on the conventionalwisdom of the divided governmentargument,
some reformershoping to alleviatelegislativegridlockhave advocatedchangesin
the electoral system designed to promote unified government (see Sundquist
1992). Yet the resultsof this study suggest that adoptingsuch changes may not
help to reduce gridlock, since unified governmentis not necessarilyany less
prone to gridlock than divided government.A more effectivestrategyfor those
who desire active governmentmay be to reduce the threatof filibustersby lowering the three-fifthscloture requirement.Ironically,however,lowering the cloture requirementrequiresa vote of two-thirdsof the Senate,a level of agreement
that is unlikely to be reachedin the currentera of partypolarization.
APPENDIX:MAJORLEGISLATIVE
PROPOSALS
105thCongress
bankruptcyrevisions
managedcare
partialbirth abortion
supplementalapprop. 1997
budget reconcil.-spend.1998
budget reconcil.-taxes1998
defense authorization1998
supplementalapprop. 1998
defense authorization1999
higher education
housing overhaul
interet tax
IRSrestructuring
transportation
1Q4thCongress
balancedbudget
flag desecration
StateDept., for. aid 1996-97
job training
budget reconciliation1996
productliability
regulatoryoverhaul
term limits
anti-terrorism/death
appeals
congressionalcompliance
defense authorization1996
defense authorization1997
farmbill
recissions 1995
health insurance
immigration
line item veto
lobbying
paperworkreduction
safe drinkingwater
shareholderlawsuits
minimumwage hike
telecommunications
unfunded mandates
welfarereform
103rdCongress
campaignfinance
lobbying
137
PoliticalResearch
Quarterly
EPAcabinetposition
abortionclinic access
Bradybill
budget reconcil. 1993
defense authorization1994
defense authorization1995
economic stimuluspackage
educationreauthorization
family& medicalleave
GATT
Goals 2000
HatchAct
independentcounsel
motor voter
NAFTA
nationalservice
NIH reauthorization
omnibus crime
savings& loan bailout
unemploymentbenefits
102ndCongress
crime bill
educationgoals
strikerreplacement
urbanaid tax bill 1992
campaignfinancereform
China-MFN
motor voter
familyleave
gag rule
middle class tax cut 1992
NIH reauthorization
balancedbudget
foreignaid auth. 1992-3
verticalprice fixing
bankingoverhaul
cable TV regulation
civil rights
defense authorization1992
DesertStormsupplemental
energypolicy
federalwaste compliance
higher educationreauth.
RTCfinancing
Russianaid
disasterrelief
supplementalauth. 1991
surfacetransportation
unemploymentbenefits
use of force in Gulf
101st Congress
civil rights
HatchAct revisions
textile & appareltrade
campaignfinancereform
age discrimination
clean air
contraaid
defense authorization1989
defense authorization1990
disabilitiesact
farmprograms
housing programs
legal immigrationrevision
minimumwage increase
Nicaraguaelection aid
oil-spill liability
Poland,Hungaryaid
budget reconciliation1990
thriftbailout/reform
vocationaleducation
100thCongress
airportreauthorization
catastrophichealth care
GroveCity civil rights
clean wateract
contraaid
G-R-Hrevisions
defense authorization1989
droughtrelief
fairhousing
138
andLegislative
Gridlock
PartyPolarization
farmcredit
FSLICrecapitalization
defense authorization1988
budget reconciliation1988
highwayreauthorization
homeless aid
housing authorization
omnibus drug
omnibus trade
plant closings/notice
welfarereform
foreignaid auth. 1982
highways/masstransit
militarypay
nuclearwaste
omnibus farmbill
budget reconciliation1983
budget reconcil.-spend.1982
social security
supplementalapprop. 1982
tax cut
voting rightsact
99th Congress
clean wateract extension
emergencyfarmcredit
budget reconciliation1986
defense authorization1986
farmbill
foreignaid authorization1985
Gramm-Rudman
budget act
reform
immigration
MXmissile appropriation
MXmissile authorization
South Africasanctions
contraaid
superfundreauthorization
tax reform
96th Congress
energymobilizationboard
Alaskalands
banking/NOWaccounts
Chrysleraid
educationdepartment
food stamp spending cap
FederalTradeCommission
Genevatradeagreements
nuclearenergy
railroadderegulation
syntheticfuels
Taiwanrelations
truckingderegulation
windfallprofits
98th Congress
immigration
defense authorization
deficit reduction
housing authorization
revenuesharing
social security/medicare
emergencyjobs program
95th Congress
laborlaw revision
campaignfinancing
aid for education
airlinederegulation
Arabboycott
civil servicereform
clean air amendments
emergencynaturalgas
energydepartment
financialdisclosure
Humphrey-Hawkins
minimumwage
nationalenergyact
97th Congress
oil allocation
balancedbudget amend.
defense authorization1983
budget reconcil.-taxes1982
139
PoliticalResearch
Ouarterlv
New YorkCity aid
omnibus farm-foodbill
public worksjobs
reorganizationauthority
social securityfinancing
stimulustax cuts 1977
strip mining
tax cuts 1978
waterpollution control
94th Congress
clean air
common-sitepicketing
consumeragency
farmsupports
lobby reform
naturalgas
strip mining
Vietnamcontingencyact
arms sales/militaryaid
educationaid
emergencyhousing
energyconservation& oil
FECchanges
food stamp price freeze
northeastrail assistance
New YorkCity aid
public servicejobs
public worksjobs
railroadreorganization
revenuesharing
tax reduction
tax revision
Vietnamrefugeerelief
voting rights
REFERENCES
Binder,Sarah.1999. "TheDynamicsof LegislativeGridlock,1947-1996."AmericanPoliticalScienceReview93: 519-36.
PoliticsandPolicyfrom
Brady,David, and CraigVolden. 1998. RevolvingGridlock:
Carterto Clinton.Boulder,CO:WestviewPress.
Cameron,Charles,William Howell, Scott Adler, and CharlesRiemann. 1997.
"DividedGovernmentand the LegislativeProductivityof Congress, 19451994."Paperpresentedat the annualmeeting of the AmericanPoliticalScience Association,Washington,DC.
Coleman,John J. 1999. "UnifiedGovernment,Divided Government,and Party
AmericanPoliticalScienceReview93: 821-35.
Responsiveness."
Cutler,LloydN. 1988. "SomeReflectionsAbout DividedGovernment."Presidential StudiesQuarterly17: 485-92.
Edwards,GeorgeC. III,AndrewBarrett,and JeffreyPeake. 1997. "TheLegislative Impactof Divided Government."American
Journalof PoliticalScience41:
545-63.
and the President'sQuest
Fleisher,Richard,andJon R. Bond. 2000. "Partisanship
for Votes on the Floor of Congress."In Jon R. Bond and RichardFleisher,
eds., PolarizedPolitics:Congressand the Presidentin a PartisanEra.Washington, DC: CQ Press
Hagle, TimothyM., and Glenn E. MitchellII. 1992. "Goodnessof Fit Measures
for Probitand Logit."AmericanJournal
of PoliticalScience36: 762-84.
140
andLegislative
Gridlock
PartyPolarization
Jones, David R. 1995. "ExplainingPolicy Stabilityin the United States:Divided
Governmentor Partisanshipin the House?"Paperpresentedat the annual
meeting of the MidwestPoliticalScienceAssociation,Chicago.
. 1998. "Partiesand the Volume of Law Production, 1947-1994." Presented at the annual meeting of the MidwestPoliticalScience Association,
Chicago,IL.
Kelly,Sean Q. 1993. "DividedWe Govern?A Reassessment."Polity25 :473-84.
Kernell,Samuel. 1991. "Facingan OppositionCongress:The President'sStrategic Circumstance."In GaryW Cox and SamuelKerell, eds., ThePoliticsof
DividedGovernment,
pp. 97-112. San Francisco,CA:WestviewPress.
A
Indi1997.
Solution
to theEcological
Problem:
King,Gary.
Inference
Reconstructing
vidualBehaviorFromAggregateData. Princeton, NJ: Princeton University
Press.
Kingdon,John W 1984. Agendas,Alternatives,and PublicPolicies.Boston:Little
Brown.
Krehbiel,Keith. 1998. PivotalPolitics.Chicago:Universityof ChicagoPress.
Mayhew,David R. 1991. DividedWeGovern.New Haven:YaleUniversityPress.
A Political-Economic
HisPoole, KeithT. and HowardRosenthal.1997. Congress:
toryof RollCallVoting.New York:OxfordUniversityPress.
Z4ewLegislativeProcessesin the
Sinclair,Barbara.1997. UnorthodoxLawmaking:
U.S. Congress.Washington,DC: CQ Press.
Sundquist,JamesL. 1988. "Needed:A PoliticalTheoryfor the New Eraof Coalition Governmentin the United States."PoliticalScienceQuarterly103: 61424.
rev.ed. Washing_ . 1992. Constitutional
Reformand EffectiveGovernment,
ton, DC: BrookingsInstitution.
AmericanPolitics
Taylor,AndrewJ. 1998. "ExplainingGovernmentProductivity."
Quarterly26: 439-58.
Received:July 19, 1999
Acceptedfor Publication:July 5, 2000
davidjonesl @baruch.cuny.edu
141