Centrist's curse? An electoral competition model with credibility constraints

Abstract

I analyze a model of electoral competition in which a candidate's reputation and his need of credibility restricts his policy choice to a certain subset of the policy space, its ideology set. Candidates are office-motivated. They care about winning and also about the share of votes they get. I consider both two and three party systems. I describe the equilibrium outcomes assuming that plurality rule applies, and obtain for two party competition, in some cases, equilibrium outcomes different than what the median voter theorem suggests because of the restrictions on the ideology sets implied by the credibility constraints. I show that centrist parties are disadvantaged compared to leftist and rightist ones, since, in equilibrium, leftist and rightist parties choose policy points that are as close as possible to each other and obtain votes from the centrist parties' ideology set. A centrist candidate needs a higher concentration of voters in his credibility set compared to his opponents in order to have a chance to win. I also analyze a run-off system for three parties and show that centrist parties have more opportunities to win under this rule than under plurality rule.