Explaining the Party Unity of Governing Parties in Mexico

  • Yen-Pin Su National Chengchi University, Taiwan
  • Fabricio A. Fonseca Tamkang University, Taiwan
Palabras clave: Party Unity, Presidential Approval, Institutional Revolutionary Party, Legislative Voting, Mexico



Previous studies have found that party unity in legislative voting tends to be higher for governing parties, but little is known about why some governing parties have higher levels of party unity than others. This study aims to fill the empirical void by conducting analyses of governing parties’ unity in legislative voting. We argue that presidential popularity matters for explaining variation in vote unity of governing parties because presidential approval is an important psychological component in executive-legislative relations. Focusing on deputies from the incumbent parties in roll-call votes for executive-sponsored bills in Mexico from 1998 through 2018, we find that the level of a governing party’s unity increases with higher presidential approval. The results are robust to a number of sensitivity tests and to controlling for potential endogeneity.

Biografía del autor/a

Yen-Pin Su, National Chengchi University, Taiwan


Yen-Pin Su is Associate Professor in the Department of Political Science at National Chengchi University. He holds a Ph.D. in Political Science from the University of Pittsburgh. He specializes in comparative politics and political behavior, with a regional focus of Latin America. His research has been published in Comparative Politics, Party Politics, International Political Science Review, Latin American Politics and Society, and other outlets. Email: yenpinsu@nccu.edu.tw

Fabricio A. Fonseca, Tamkang University, Taiwan


Fabricio A. Fonseca is Assistant Professor in the Graduate Institute of Latin American Studies at Tamkang University. He holds a Ph.D. in Asia-Pacific Studies from National Chengchi University. His research interests include international relations, political economy, and comparative politics between East Asia and Latin America, particularly topics on Taiwan and Mexico. Email: faban.fonseca@gmail.com

Cómo citar
Su, Y.-P., & Fonseca, F. A. (2021). Explaining the Party Unity of Governing Parties in Mexico. Revista De Ciencia Política, 41(3), 515-537. https://doi.org/10.4067/S0718-090X2021005000111