Any theoretically informed predictions about the future of international order and global governance must reckon with the power and intentions of the United States. We argue that fundamental changes in the nature of domestic audience constraint within many democracies, and the United States in particular, undermine both the willingness and the capability of the United States to continue its role as the underwriter of international order and global governance. A US government unbound by domestic constraint will have difficulty building broad coalitions to solve national and international problems because it will have reduced incentives to invest in public goods, including national defense, science and technology, and future economic prosperity; reduced barriers to corruption that undermines the quality of and trust in US capabilities; and reduced state capacity, including the capacity to finance wars and other long-term international commitments. We argue that three trends were especially relevant in reshaping domestic audience constraint: information fragmentation, extreme polarization, and a global threat environment that facilitated executive power concentration. Together they reduce the costs and risks for leaders to escape domestic audience constraints, weakening the institutional and accountability mechanisms that give democracies advantages in the international system. Though these trends affect many democracies, the undermining of US domestic constraint is particularly consequential because the United States shaped and buttressed the current system. An unconstrained United States likely means a less cooperative and less predictable global order, irrevocably altering the post-1945 system.