President Vs Ruling Party: Causes of Policy Preference Divergence in Presidential Democracies

It is intuitive to think that presidents and their affiliated ruling parties share the same policy preferences. However, presidents often distance themselves from their own parties and diverge in policy position and salience. For instance, research using expert survey data from South American countries shows that presidents’ left-right ideological and policy positions frequently differ from those of their parties (Wiesehomeier and Benoit, 2009; Shim and Farag, 2024). Understanding the policy preference divergence between presidents and their ruling parties is crucial in politics, as it can lead to internal party conflicts, impact party cohesion and electoral success, and affect policy continuity within a government (Shugart and Carey, 1992; Haggard and McCubbins, 2001; Samuels and Shugart, 2010). Against this background, the paper aims to theorise and test the causes behind preference divergence between presidents and ruling parties in presidential democracies. Drawing from the presidential politics scholarship, we focus on several potential reasons related to elections (e.g., differences in electoral district size, election method, election timing), accountability (e.g., differences in term limits and ruling party seat share), the president’s outsider status, and the level of ruling party institutionalization (e.g., a new vehicle party by the president or an institutionalized party with other heavyweights). The theorized causes are tested using the 2021 Chapel Hill Expert Survey, which includes data from 12 Latin American countries and measures the policy preferences of both parties and presidents from the perspective of position and salience. Regression analyses will be employed to identify the factors affecting the degree of preference divergence. This paper contributes to the presidential politics literature by providing a comprehensive theoretical framework to explain the causes of policy preference divergence between presidents and their affiliated ruling parties in presidential democracies.