Presidential power and party strength: The "inverse relationship" reconsidered

Abstract

This article revisits theoretical claims that separation of power systems will display an inverse relationship between presidential power and party strength. Shugart and Carey posited this as a general equilibrium within presidential democracies; later, Shugart proposed that the inverse relationship resulted from founding institutional choices shaped in turn by modes of democratic transition. We test both the equilibrium and the genetic versions of the inverse relationship on a large-N dataset of presidential systems from 1900 to 2016. We find strong significant empirical support for an inverse relationship between executive power and party system institutionalization. However, the relationship is more dynamic than would be predicted by theories based on institutional foundings alone. Through analysis of decree reform in Argentina and Brazil, we observe changes in the expected inverse relationship despite the absence of a constitutional assembly and the lack of any change in electoral rules or party authority.