In elections, parties do not just state their positions on the left-right ideological spectrum; parties also use rhetorical strategies to frame their messages in convincing ways. However, we lack good understanding of the role that rhetoric plays in party competition. To address the lacuna, my book project focuses on parties’ use of moral rhetoric and investigates its consequences on voter behavior. Based on insights from political and moral psychology, I argue that moral rhetoric can mobilize copartisan voters and that the mobilizing effect occurs because moral rhetoric increases the positive emotions that copartisans have about their partisan preference. I expect the relationship to hold among copartisans who are exposed to party rhetoric. To test my argument, I text analyze party manifestos to measure the overall level of moral rhetoric that parties used in elections and use survey data to measure turnout among copartisan voters. The data cover 61 parties across 18 elections from six English-speaking democracies. I find evidence in support of my argument that moral rhetoric mobilizes copartisan voters who are likely to have been exposed to party rhetoric.

I also test the theoretical mechanism through two sets of analyses. First, I conducted survey experiments in Britain and find that messages that contain moral rhetoric have a positively emotionally activating effect on copartisan voters compared to messages that contain non-moral, pragmatic rhetoric. Second, I analyze panel data in the 2015 British Election Study and show that having positive emotions about one’s party increases the probability of turnout and political activism. The analyses provide evidence in support of the theoretical mechanism that positive emotions mediate the link between moral rhetoric and mobilization.

My book project contributes to a broad array of research areas, including party campaigns, morality and politics, and emotions and political participation. However, most importantly, it pushes the boundaries of research on comparative party politics. My project is the first to cross-nationally measure moral rhetoric and provide evidence of its significance for voter behavior. By showing the importance of how parties explain and justify their positions to voters, it opens the door to an exciting research trajectory on a thus far overlooked aspect of comparative party behavior.