Distributive Politics with Primaries

We develop a model of electoral competition in which two parties compete for votes amongst three groups of voters. Each party first internally selects one of two candidates to run in a general election. Candidates within a party share a fixed ideological platform and can promise a distribution of a unit of public spending across groups. Without primary elections, the selection process is random. With primary elections, an ideologically friendly subset of the voters strategically chooses the candidate. In the basic model, primary elections cause politicians to cater to extreme groups rather than a moderate group with many "swing voters." The amount promised to extreme groups is decreasing in the ideological polarization of those groups, while each party's probability of victory is increasing in the size and extremity of its favored group. We also find that an incumbency advantage reduces the amount promised to extremists, and therefore benefits moderates.