Extreme • This is because when the positions of both candidates are extreme, the latter will find it important that the nominee of this party will not win the election. • As a result, they strategically vote for tile candidate who is more extreme and has less chance to win the election Extreme • On the other hand, the party members also realize that the more extreme candidate has very little chance to win, and the desire to win the election will surpass their fondness of a candidate. • Consequently, they vote for the moderate candidate. • We find that the more extreme the positions of the candidates are, the more likely the voters will vote strategically. Side report • However, whether the strategic voting behavior affects the outcome of the primary depends upon the relative turnout rate of party and nonparty members in the primary. • The welfare implication of the strategic voting behavior will also be discussed layout • The remainder of the paper is organised as follows. Section 2 gives the model. Section 3 analyzes the equilibrium outcome under various assumptions on the voters' strategic behavior • Section 4 discusses the welfare implications of strategic voting. • Section 5 derives some empirical implications of the model. Section 6 discusses and relaxes the assumptions made in the model, and finds that most of the qualitative results still holds. Section 7 concludes.