Miami Herald, FL 06-20-07 Iowa poll gives Clinton slight edge, suggests GOP shift A poll brought good news for the campaign of Sen. Hillary Clinton and surprising results for Republicans. BY WILLIAM DOUGLAS Sen. Hillary Clinton has inched ahead of former Sen. John Edwards in a tightening Democratic presidential race in Iowa, while the Republican race is shifting in surprising ways, according to a new poll made available exclusively to McClatchy News Service and NBC News. The poll by Mason-Dixon Polling and Research Inc. showed that Clinton, D-N.Y., has the support of 22 percent of likely caucus voters in Iowa, with Edwards, DN.C., right on her heels at 21 percent. Illinois Sen. Barack Obama was third at 18 percent. New Mexico Gov. Bill Richardson placed fourth with 6 percent. Edwards had an average 3 percentage-point lead over Clinton in Iowa last month in five national polls, with Obama an average 7 points behind Edwards. Clinton's small lead in the Mason-Dixon poll falls within the survey's margin of error -- plus or minus 5 percentage points -- but indicates support for her is growing in the state that will hold the first nominating contest for Democratic and Republican presidential candidates, on Jan. 14. The Mason-Dixon poll also revealed some seismic shifts among Republican candidates, with one undeclared candidate gaining serious ground and two toptier candidates slipping badly. Former Massachusetts Gov. Mitt Romney led the field with 25 percent. Former Tennessee Sen. Fred Thompson, who has yet to formally enter the race, polled 17 percent. Former New York Mayor Rudy Giuliani had 15 percent. Former Arkansas Gov. Mike Huckabee placed fourth at 7 percent. Sen. John McCain, R-Ariz., once considered the favorite to win the Republican nomination, won only 6 percent support from likely Republican caucus voters in Iowa, tying him with Sen. Sam Brownback, R-Kan. McCain's fall in Iowa has been steep: He enjoyed average support of 19 percent in five national polls last month, only 1.2 points less than front-runner Romney, according to RealClear Politics.com. Giuliani also appears to be losing altitude; he averaged 18.6 support in five Iowa polls last month. McCain also slipped badly in a Mason-Dixon poll of South Carolina Republicans released last weekend, to fourth place with only 7 percent support. Thompson led with 25 percent. McCain's staunch support for the war in Iraq and comprehensive immigration restructuring may be weighing him down. Dianne Bystrom, a political science professor at Iowa State University, said the shift among Republican candidates was rooted in decisions by McCain and Giuliani to bypass the Iowa straw poll in August. Romney has committed to attend the event, which is a big fundraiser for the state Republican party.