What varies? Public opinion, salience, and political entrepreneurism across EU trade agreements and member states

In the wake of public opposition to trade agreement negotiations with the United States and Canada, EU scholars began to wrestle with the prospect that another subfield of quiet politics had been thrust into the limelight. A raft of articles have been published since, explaining drops in public opinion along with the motivations for contestation; the success of contestation campaigns; or their effects on support for different policy positions by political entrepreneurs. Several research agendas orient the academic puzzle of what has caused politicization or increased salience of EU trade policy in a comparative direction – focusing on variation between member states and across agreements. But what will be explained through this comparative approach? Politicization, salience, public opinion, contestation or political support and entrepreneurism? Already, the overlapping nature of all these explananda stifles our capacity to take up the challenge of pursuing a rigorous comparative analysis. But what is most surprising is that in spite of academic interest in reactions to EU trade agreement negotiations, there is still no systematic account of the variation that exists among the related phenomena which are to be explained. This paper begins from the premise that theoretical interest is borne of empirical observation: that a puzzle only emerges once some perplexing variation has been established. It describes the specific phenomena which have been called upon to demonstrate that contestation, public opinion, political support, salience or indeed politicization have changed over time or place. The question is simple: what varies? Or rather, what has varied to such an extent that scholars might now see the field of EU trade policy as undergoing a mystifying upheaval that requires explanation? Through a systematic comparison of four data sets across all EU member states in relation to six trade agreement negotiations from 2009-2021, it demonstrates that all of the data operationalized in existing studies to treat politicization as an ordinal variable have glossed over important distinctions in what was actually being observed. It identifies a set of six categorically distinct processes drawn from the data which describe the observed variation in politicization and considers their ongoing relevance in the field.