The EU has become more salient on the agenda of both media and parties as the integration process has developed towards more integration. However, there is a large variance within this trend. A patchwork of politicizing moments has happened whenever a critical or exceptional moment hits, directly or indirectly, the institution. Additionally, this literature has also been inquiring into the polarization of the EU on both media and parties and also on which issues were politicized at different moments.

In parallel, politics has become increasingly mediatized with media being the most important source of information and communication between governors and the governed. Despite this intricate connection, parties and media have different underlying motivations that impact not only on the contents that both arenas focus on but also on the way they do so. These distinct characteristics between both actors have the potential to trigger different patterns of politicization regarding salience, polarization, content (different EU issues), and format with variation across countries and over time. Past literature neglects a necessary comparison of both arenas and several aspects of EU politicization can only be understood in this way. Therefore, this paper assesses the EU politicization phenomenon on its several aspects (salience, polarization, content, and format) on both arenas (parties and media), and over time (from 2002 to 2016) in five different countries (Portugal, Spain, Germany, Ireland, and Belgium). Through the application of automated and manual content analysis realized by native speakers, both parliamentary debates and newspapers are analyzed.