This article investigates how public policy responds to persistent ideological shifts in dynamic politico-economic equilibria. To this end, I develop a tractable model to analyze the dynamic interactions among public policy, individuals’ intertemporal choice, and the evolution of political constituency. My main finding is that a right-wing ideology may increase the size of government. Data from a panel of 18 OECD countries confirm that after controlling for the partisan effect, there is a positive relationship between the right-wing political constituency and government size. This is consistent with my theoretical prediction, but hard to explain by existing theories.