What does European Union Politics Look Like: Ideology, Values, Both?

How has the political space in European Union politics evolved and has left-right politics been replaced by a value based pro-EU - anti-system dimension? In this paper, we address this question. Based on rollcall data for all European Parliaments from 1979 to 2024, we estimate dynamic ideal points in six months intervals for all Members of the European Parliament (MEPs). We compare our method to the standard procedure where ideal points are estimated in two dimensions, separately for each legislative term and, hence, not comparable over time. Contrary to conventional wisdom, we demonstrate that over 90 percent of variation in voting behaviour is explained by one dominant ideological dimension – a trend that persists even with an influx of Euroskeptic MEPs, the politicization of EU politics and throughout periods affected by Brexit and the COVID-19 pandemic. We contribute to the literature on the dimensionality of politics in the EU and in addition, we provide the longest time-series of European Parliament legislator ideal points and uncertainty estimates. Contrary to the standard procedure, our ideal points are comparable over time and, therefore, more useful for scholars of legislative politics.