Mutual Party Extremism

It is well known that candidates may have to stake out more partisan positions to win their primaries. These then also determine their success in the general election. The equilibrium consequences of primaries are less well understood. There is a robust externality — the primary trap — that can sustain multiple equilibria (along a band). Candidate extremism (moderation) on one side facilitates candidate extremism (moderation) on the other. Electorate polarization and turnout are less important than other candidates’ choices. The paper also discusses how other considerations can alter the set of equilibria.