A Theory and Test of Pledge-Based Voting: The Limited but Real Effects of Election Pledges on Citizens’ Vote Choice

Abstract

Do voters decide on the basis of the election pledges political parties make? Although this is a key assumption in most democratic theories and, seemingly, among parties who issue dozens of pledges during campaigns, the scientific literature does not provide a clear answer to this question. This article develops a theory of pledge-based voting and a research design that allows for studying the electoral effects of pledges in real-time as the campaign unfolds. Based on a novel experimental design embedded in panel surveys administered during and after the 2019 Danish national election campaign (N = 6233), we estimate that the most salient pledges affect vote choice by between 1.1 and 2.1 percentage points averaged across the electorate. While modest, these effects can be decisive in the often highly competitive context of modern elections. The findings have implications for our understanding of political behavior, party politics, and normative theories of democracy.