Kingmakers or Cheerleaders? Party Power and the Causal Effects of Endorsements

Abstract

When parties make endorsements in primary elections, does the favored candidate receive a real boost in her vote share, or do parties simply pick the favorites who are already destined to win? That is, do parties act as kingmakers who swing elections or cheerleaders who merely root on the winning side? To answer this question, we draw on two research designs aimed at isolating the causal effect of Democratic Party endorsements in California’s 2012 primary election. First, we conduct a survey experiment in which we randomly assign a party endorsement, holding all other aspects of a candidate’s background and policy positions constant. Second, we use a unique dataset to implement a regression-discontinuity analysis of electoral trends by comparing the vote shares captured by candidates who barely won or barely lost the internal party endorsement contest. We find that endorsements do indeed matter, though the magnitude of their impact is smaller than might be estimated from research designs less attuned to recent advances in causal inference.

Keywords: endorsements, parties, California, primaries