Politicising Europe on Social Media: Political Opportunity Structures and EU Issue Salience in Central and Eastern Europe

This article examines when and under what conditions political leaders in Central and Eastern Europe (CEE) politicise European integration in their routine social media communication. Building on post-functionalist theory and the political opportunity structure perspective, we focus on the salience dimension of politicisation and ask: (1) how extensive is EU issue salience in party leaders’ communication over time, and (2) which aspects of political opportunity structures account for its temporal variation. We analyse an original dataset of 181,615 tweets posted between 2007 and 2022 by leaders of politically relevant parties in five CEE countries (Czechia, Estonia, Poland, Slovakia, Slovenia) and Germany, used as a Western European reference case. EU-related tweets are identified through automated retrieval and manual content coding, enabling the measurement of absolute and relative EU salience. The resulting time-series cross-sectional data are modelled using two-way fixed-effects specifications. Descriptively, EU salience on leaders’ Twitter accounts is negligible before 2011 but subsequently follows a punctuated trajectory, with an upward drift and pronounced peaks in 2011, 2014 and 2019. These patterns are consistent with the notion of “politicising moments” and align with evidence from parliamentary debates and news media, while highlighting the added value of continuous, unmediated social media data for capturing short-term, event-driven fluctuations. Substantively, our analyses show that specific opportunity structures strongly condition politicisation. European Parliament elections are the strongest driver. In the run-up to EP contests, the likelihood that a tweet is EU-related more than doubles. EU-related referendums, including Brexit, and European Council summits also increase EU-related communication, indicating that focal, leader-centric events play a key role in structuring EU salience. By contrast, other hypothesised opportunity structures exert weaker or counter-intuitive effects. EU salience declines ahead of national parliamentary elections, suggesting that party leaders strategically prioritise domestic concerns in national campaigns. Routine EU milestones, such as Council presidencies and Commission appointments, do not consistently elevate EU salience after controlling for EP elections. Nor do the Eurozone and refugee crises, or levels of public Euroscepticism, substantively and statistically significantly associate with EU-related tweeting. Overall, the study confirms that the politicisation of European integration on party leaders’ social media is cyclical and event-driven, but with its intensity and triggers displaying clear CEE-specific nuances compared to Western Europe.