The Effects of Co-governing and Party Size on Ideological Convergence
Previous literature has investigated how coalition parties diverge ideologically during elections while converge in-between elections. However, less attention has been devoted to the ideological convergence of co-governing parties in the long term. Using data from 36 parliamentary democracies in the 1948-2019 period, I demonstrate that cabinet parties tend to converge ideologically across elections. I claim that such strategic behavior is due to the coalition bargaining process and the design and implementation of common public policies that pushes parties to internalize diverse views. Additionally, I show that parties’ relative size—a variable until now neglected by the literature—is also associated with such convergence. Specifically, as the difference of vote share between parties increases, we observe higher levels of ideological convergence regardless of cabinet/opposition membership. This suggests that smaller parties have incentives to adopt policies that have proven popular when implemented by mainstream parties.