In this article, I elaborate a conceptual innovation that underlies, if only in nascent form, Jürgen Habermas's notion of pouvoir constituant mixte and could significantly advance research on the democratic legitimacy of EU constitutional politics: the levelling up of constituent power. According to this idea, state‐level pouvoirs constituants may issue an authorization for constitutional decision‐making at the supra‐state level and thereby bring about a new constituent power whose composition can take a variety of forms. This conceptual framework paves the way for a systematic analysis of the EU's pouvoir constituant and its relation to the demoi of the member states. At the same time, it renders it an open normative question of who should be in charge of EU constitutional politics.