Populist Leaders Reshape Party Positions Across 51 Democracies

What the Paper Asks

Marcel Garz and Tanmay Singh investigate how the rise of populist state leaders—not just populist parties in parliament—affects where mainstream parties place themselves on key issues. The paper focuses on whether the presence of a populist head of state or government shifts party competition, especially on culturally charged topics like multiculturalism, with implications for polarization.

Data and Measurement

The authors analyze party manifestos from 51 democratic countries spanning 1989–2018. They combine traditional content-analytical coding with large language models to measure the positions parties express in their manifestos across multiple policy domains. This approach yields fine-grained, comparable measures of party rhetoric over time and across systems.

Research Design and Methods

Using methods for causal inference with observational data, the study estimates how mainstream parties adjust their stated positions after a populist becomes the national leader. The design leverages cross-national variation in the timing and ideological orientation of populist leaders and controls for contextual factors to isolate likely causal effects on party positioning.

Key Findings

• Right-wing populist state leaders tend to push mainstream parties to differentiate their positions on multiculturalism, a dynamic that can increase polarization within the party system.
• Under left-wing populist leaders, mainstream parties' responses are more mixed: they sometimes converge (become more homogeneous) and sometimes differentiate, depending on the policy category and contextual moderators.

Where Effects Are Stronger

The authors find that mainstream parties are generally more responsive to populist leaders in emerging democracies than in advanced democracies, and in presidential systems compared with parliamentary systems. These institutional and development-level differences condition how parties reposition in response to a populist head of state or government.

Implications for Party Competition

The study shows that the ideological orientation of populist leaders matters for how party systems evolve: right-wing leaders tend to pull parties apart on cultural issues, while left-wing leaders produce more variable effects. By combining manifesto analysis with modern text methods and careful causal inference, Garz and Singh provide new evidence that executive-level populism can reshape party competition across a wide set of democracies.