Partisan Dynamics in Presidential Primaries and Campaign Divisiveness

Abstract

Observers have noted that the Republican and Democratic primaries differ substantially, with Republicans typically having an easier time selecting their nominee. Previous research has suggested that this may be attributable to Republican Party homogeneity and delegate allocation rules that winnow candidates faster, but there is little empirical evidence on how these factors influence the primary process. Rather than predicting overall vote share or the nominee, I examine the temporal dynamics of each party’s primary campaigns. I show that Republican candidates are over-rewarded for winning elections, while Democrats are rewarded for performing well overall. The result is that late in the campaign, Republicans are much more likely to exit as compared with Democrats, and there is little evidence that these dynamics have changed over time. I conclude that the Republican Party produces systematically shorter and less divisive primaries as a result of its faster and more efficient winnowing process.