Flip-Flopping: Ideological Adjustment Costs in the United States Senate

Abstract

Models of electoral competition in which candidates can change position at no cost predict the convergence of platforms in a two-candidate election. Such convergence is at odds with empirical observation. In this paper, I undertake a study of candidate positioning in the United States Senate and determine the extent to which electoral costs associated with changing position explain the ideological positions taken by Senators. Using over 50 years of roll call voting data, I use a simulated method of moments approach to estimate a dynamic model of candidate positioning for U.S. Senators. The findings support a model in which Senators face convex costs to changing position, with the best fitting model being one with linear costs of adjustment. The model thus predicts severe punishments for “flip-flopping” Senators (those who make large changes in position). As a result of the significant costs associated with adjusting position, the empirical validity of the Median Voter Theorem (which depends upon candidates being able to change position at no cost) is called into question.spatial models, dynamic political economy, Senate, ideology