Ideological extremism and primaries

This paper is the first one to present a 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 open primaries. This 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, open-primary nominees are more likely to be extremists than closed-primary ones—which is consistent with the most recent empirical evidence. 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.