Political institutions define the allocation of decision-making authority among officeholders. Institutional position is empowering, but the preferences of each actor thus empowered also constrain what others can achieve. I argue that the combination of institutional prerogative and preference-imposed constraints gives policy makers incentives to adapt their priorities (and thus their revealed preferences) to both institutional structures and the preferences and priorities of other policy makers. Officeholders who must cooperate to make policy will invest resources and suffer losses, both to help counterparts they agree with to hold on to office and to make it more difficult to do so for counterparts with whom they do not agree. My argument rests on the assumptions that a) political actors have policy goals, but they can achieve their goals only if others in the policy process support them; and b) political actors compete for and retain power by working for the benefit of those who put them in office. When decision-making authority is split among several actors, decision makers are motivated not only to take each other’s preferences into account, but also to tailor proposals to help (or hinder) each other’s ability to retain office.