Party Decay and Democratic Backsliding

What explains the contemporary wave of democratic backsliding? This article argues that party decay-the erosion of party institutionalization-is a critical catalyst. Drawing on global longitudinal data from 1970 to 2024, we construct dynamic decline indices that measure how far party institutionalization and democratic quality have fallen from their country-specific historical maxima. Employing lead-lag models, local projections, and instrumental variable estimation, we demonstrate that party decay robustly precedes and predicts subsequent democratic backsliding. This relationship is asymmetric: the forward effect of party decay on democratic backsliding is two to three times larger than the reverse effect, and robustness tests rule out mechanical or spurious correlation. Heterogeneity analyzes further show that party decay has reemerged as an increasingly relevant driver in the twenty-first century and matters across all regime types, though its impact is largest in closed autocracies. These findings refine theoretical understandings of democratic backsliding, bridge the literature on party institutionalization and democratic backsliding, and suggest that party strengthening deserves a prominent place in the promotion of democracy.