Initially unfolding in parallel ways, the Europeanization and the regionalization of politics have increasingly intersected. Regional authorities have organized themselves to affect policy developments at the supranational level. They do so through the internal restructuring of their administrations, by carrying lobbying activities directly in Brussels, but also by institutionalizing and sometimes constitutionalizing their authority over their Member State's EU position. In other words, both their informal and formal influence over EU affairs has grown. The relevance of these trends is illustrated by recent events such as the Wallonia parliament holding up the EU–Canada trade deal. This case highlights how the nature of both subnational and supranational politics has changed over time. International trade deals used to be considered as ‘high politics’, remote from the immediate concerns of regional bodies and well beyond their formal reach. The Wallonia case illustrates this is no longer so.