American observers of international affairs are currently enmeshed in a debate on the future of global order and leadership. For at least a decade, it has been debated whether the global center of power and leadership is gradually shifting away from the ‘declining’ West towards ‘rising’ powers like the BRICS and what consequences this may have for global order, governance and leadership. This paper examines this ongoing debate on the future of global leadership among American observers of international affairs. It finds two main changes in this discourse. First, with the election of President Trump and Brexit—and the resulting uncertainties over the future of NATO, the EU, free trade and climate agreements—there is now a more urgent sense that we are not only witnessing the rise of new powers but the decline of the so-called ‘liberal international order’ installed after World War II. Second, and most remarkably, the order is collapsing by way of abdication rather than a hegemonic clash between rising and declining powers. Third, and as a consequence, the discourse on a global leadership vacuum, turmoil and world disorder is gaining prominence. The paper argues that diagnoses of the coming of a ‘leaderless’ or ‘G-Zero’ world are never only neutral observations of world politics, but also political moves. As such, the narrative of a leadership vacuum can be deployed politically to, variously, call for multilateral engagement, global governance, stronger unilateral leadership, containing aspiring leaders and so on. Moreover, the various diagnoses and prescriptions for a leadership vacuum embody more or less explicit notions of what (good) leadership is and it sees ‘the world to be lead’ from a distinct perspective. By examining these contemporary debates on global leadership among American intellectuals and policymakers, it sheds light on the broader politics of ‘declinism’ and a ‘leaderless world’.