What is the impact of democratic transition on the party politics of neighboring democratic nations? While existing scholarship on democratic diffusion primarily focuses on how democratization influences authoritarian regimes, it often overlooks the cross-border effects on neighboring democracies. This study addresses this gap by investigating the impact of democratic transitions on party polarization and the issue salience of democracy in countries with democratic or hybrid regimes. Using the Manifesto Project and V-DEM’s regime transitions data sets and employing a difference-in-differences design with staggered treatment adoption, our analysis reveals a counterintuitive effect: democratic transitions in one country leads to a decrease in party polarization over democracy in neighboring countries. We posit this decline is a long-term phenomenon, linked to the diminishing salience of democracy as a key issue in party manifestos after a short period of initial prominence. By shifting the scholarly focus of diffusion effects to party politics within democratic and hybrid regimes, we contribute to a more nuanced understanding of how democratization ripples beyond its borders, shaping the political landscape in unanticipated ways.
Ademi et al. (2026) studied this question.