Ideological Extremism and Primaries

Agustin Casas (CUNEF)

Abstract: This paper is the first one to present a “general equilibrium” model of primaries with endogenous party affiliations. I show that closed primaries (where only affiliated party members can vote) result in more charismatic candidates than in open primaries. That occurs because, in equilibrium, closed-primary voters care more about winning and therefore they are more willing to trade off their ideologically preferred candidate for one who is more likely to win, i.e., a more charismatic one. I also show that under open primaries, the party leaders have higher incentives to choose more extreme platforms. As a consequence, and in line with the most recent empirical evidence, open-primary nominees are more likely to be extremists than closed-primary ones. Finally, I show that, if instead of organizing primaries, party leaders were to handpick the nominees, the candidates would be even more moderate and more charismatic.

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