Partisan politics : parties, primaries and elections

Parties' candidates are chosen by different nomination rules. Recent empirical evidence shows that these rules influence the attributes of the nominees; for instance, open primaries in the U.S. choose more extreme candidates than closed primaries. Despite this evidence, the literature does not provide an explanation of why appealing to a more moderate electorate -as during open primariesresults in more extreme candidates. I build a model that shows that open primaries elect \predictable extremists", while, for instance, party leaders would chose \moderate mavericks". I obtain these results through a model that puts together 3 pieces of partisan politics: affiliation decisions, nomination rules, and an observed endogenous valence, which (together with party membership) signals the candidates' ideologies. Moreover, I investigate the welfare implications of three methods: nomination by the party leader, by closed primaries, and by open primaries. I show the conditions under which nomination by party leaders leads to higher social welfare than nomination by open primaries. Furthermore, I show that higher screening by parties, leads to more ideologically uncertain candidates. In sum, I argue that party affiliation decisions, and endogenous valence play a large role in understanding the effects of nomination rules on the political equilibria.