Most scholars suggest that a popularly elected presidency undermines the stabilization of competitive party systems at the electoral and legislative level. However, little is known about how potential clashes between different partisan coalitions at the legislative and presidential arenas impede party system stabilization on the governmental/executive level—an asset of robust democracy. Such an effect is both direct (by leading to competing executive alternatives and confounding patterns of government formation, notably under powerful presidencies), and indirect (by increasing political fragmentation and hindering party institutionalization, which in turn affect governmental/executive politics). Using a mixed-methods approach, I will demonstrate these relationships using both a statistical analysis of a new dataset covering 64 European polities since 1848 and in-depth case studies (e.g., Poland, Greece, Moldova) to illustrate the causal mechanisms.