When the impact of populism on liberal democracy is examined, the focus often is on populists in power. After all, when in office, populists have the possibility to change legislation, thereby negatively affecting individual freedoms and rights, and to transform the political system, often toward democratic decline and illiberalism (Pappas 2019; Ruth-Lovell and Grahn 2023).1 Far less attention has been devoted to populist parties in opposition, even though this is the position in which populists find themselves most frequently.2 Prominent examples of Western European populist parties with a decades-long position in opposition include the Rassemblement National in France and the Vlaams Belang in Belgium on the right and Die Linke in Germany and the Socialistische Partij in the Netherlands on the left. Outside of Western Europe, populist parties often have less longevity and more frequently assume office. However, many of these parties spend years in opposition before taking on government responsibility and/or have returned to the opposition benches afterwards (e.g., Partido Justicialista in Argentina and Prawo i Sprawiedliwość in Poland).

Political party think tanks (PPTTs) are important to the performance of parties' core functions. Despite their importance, they have largely escaped academic attention. To understand the role of PPTTs in contemporary politics, we develop a typology of their key functions (distinguishing between political party and think tank functions), and target audiences (distinguishing between internal and external target groups). Based on a comprehensive literature review and 22 in-depth interviews with leading representatives of PPTTs in the Netherlands and Flanders, we identify four types of PPTTs: Party Assistants, Party Supporters, Party Promoters and Party Intellectuals. The characteristics of the four types of PPTTs are illustrated through the analysis of four paradigmatic cases: the Study Centre Open Vld as an example of a Party Assistant, the Scientific Bureau GroenLinks as an example of a Party Supporter, the Renaissance Institute as an example of a Party Promoter, and the TeldersFoundation as an example of a Party Intellectual.

With a proliferation of scholarly work focusing on populist, far-left, and far-right parties, questions have arisen about the correct ways to ideologically classify such parties. To ensure transparency and uniformity in research, the discipline could benefit from a systematic procedure. In this letter, we discuss how we have employed the method of ‘Expert-informed Qualitative Comparative Classification’ (EiQCC) to construct the newest version of The PopuList (3.0) – a database of populist, far-left, and far-right parties in Europe since 1989. This method takes into account the in-depth knowledge of national party experts while allowing for systematic comparative analysis across cases and over time. We also examine how scholars have made use of the previous versions of the dataset, explain how the new version of The PopuList differs from previous ones, and compare it to other data. We conclude with a discussion of the strengths and limitations of The PopuList dataset.

Like many party systems across Western Europe, the Dutch party system has been in flux since 2002 as a result of a series of related developments, including the decline of mainstream parties which coincided with the emergence of radical right-wing populist parties and the concurrent dimensional transformation of the political space. This article analyses how these challenges to mainstream parties fundamentally affected the structure of party competition. On the basis of content analysis of party programmes, we examine the changing configuration of the Dutch party space since 2002 and investigate the impact of these changes on coalition-formation patterns. We conclude that the Dutch party system has become increasingly unstable. It has gradually lost its core through electoral fragmentation and mainstream parties’ positional shifts. The disappearance of a core party that dominates the coalition-formation process initially transformed the direction of party competition from centripetal to centrifugal. However, since 2012 a theoretically novel configuration has emerged in which no party or coherent group of parties dominates competition.

Radical right parties are becoming increasingly likely candidates to participate in government coalitions in Western Europe. Comparative research on the electoral performance of these parties in government is still scarce. Our overview of the electoral effects of government participation of six parties in national governments shows that they do not run a higher risk of losing votes after government participation than other parties. There is considerable variation, however. Some radical right parties experienced great losses, while others won additional support. Focusing on the ways in which radical right parties conducted themselves in government, we explore why some parties won votes and others lost in post-incumbency elections. We compare their policy achievements with regard to immigration and integration policies, the performance of their ministers, and the party coherence of the six parties in office. Our analysis shows that policy records do not fully explain the variation in post-incumbency electoral results. Weak performance and internal party conflict prevent parties from credibly laying claim to the policy achievements of coalition governments and demonstrate that some of these parties were not ready for office.