Most political systems consist of multiple layers. Yet datasets are predominantly situated at a single territorial tier, encouraging methodological nationalism, regionalism, and localism. We present three new integrated datasets that include electoral, institutional, ideological, and government composition data on the country and regional level (RD|CED, RED and RPSD). With this data, we cover 337 country elections on the regional level, 2,226 regional elections, and 2,825 regional cabinets in 365 regions of 21 countries from 1941 to 2019, accounting for 800 political parties and their ideological positions. Combined, these data complement and extend existing datasets and facilitate the study of political interaction across levels. Data are available at http://multi-level-cross-level-politics.eu/ or can be accessed through the Havard Dataverse repository. We conclude with an agenda for future cross-level studies.

The rise of populist parties in Europe has generated an enormous amount of academic literature. Previous research has thoroughly examined the factors contributing to the electoral success of populist parties. Surprisingly, very little attention has been paid to the role of decentralization, one of the most widespread forms of governance in the world. This paper aims to fill this gap by presenting a theoretical and empirical account of the effect of decentralization on the electoral fortunes of populist parties in Europe. Using aggregated data from election results in 30 European countries, this paper puts competing hypotheses to the test. I argue that the mechanism linking decentralization and populist parties’ national election results is, in fact, indirect and depends on the existence of a regional tier of government. Results suggest that having representation in subnational parliaments plays a significant role in the national success of populist parties, and this effect is contingent on the degree of regional authority.

Analysis of electoral results implies in many cases differences and similarities between various areas of a polity. Differentiated electoral outcomes are evident not only within each context, but also between two (or more) territorial levels, such as elections at national, regional and provincial level, etc. Nevertheless, studying the territorial electoral discontinuities almost inevitably induces the concept of nationalisation of politics. This article presents a comparison between national and sub-national levels expressed in different electoral results between legislative and regional elections in Italy. In order to carry out a consistent analysis, the comparison of vote percentages is made by always referring to a set of seven (families of) parties, obviously modifying the choice of single parties when the offering changed, but keeping the same format for each pair of elections analysed together. The diachronic comparison over a politically relevant time span – as well as analysis at the level of geopolitical areas – gives us a useful framework rich in information. In Italy electoral behaviour in regional and national elections continues to show, albeit gradually and with some vacillations, a marked differentiation.