Retaining Political Talent: A Candidate-Centered Theory of Primary Adoption

Why do party leaders constrain their own power and allow the use of primary elections? I develop a model of intraparty politics and electoral competition in which an ambitious office-seeker reevaluates their party affiliation after their party chooses a nomination rule. The model shows that in settings in which the linkages between politicians and parties are weak, party leaders adopt primaries in order to keep potential defectors from pursuing their individual ambitions outside of the party. The main theoretical result shows that only parties that are electorally strong ex ante can use primaries as a strategy to hold their parties together. Thus, in contrast to an extensive literature linking the use of primaries to electorally weak parties, this model posits the existence of a positive relationship between the use of primaries and a party's electoral strength. Analysis of legislative and gubernatorial nominations in Mexico provides strong support for the model's expectations.