The electoral campaign leading up to the European Parliament elections significantly changes voter priorities. National allegiances become less central, while European issues gain prominence in voters' decision-making processes.

Previous studies examining the influence of EU matters on voting behavior relied solely on post-election surveys and thus could not capture campaign effects. This study introduces a novel approach by employing a rolling cross-sectional survey, enabling researchers to track shifts in voter attitudes throughout the election period.

Our findings demonstrate that campaigns actively shape European elections by informing voters about EU politics, transforming them from secondary concerns into primary factors for many electors. Voters increasingly rely on their stance toward the European project when determining whom to support, making these elections more salient and less 'second-order' in nature.