Challenger Parties in Europe: A Comparative Analysis

This study provides an innovative theoretical framework to classify and analyse parties that challenge the equilibria of their party systems. The proposed conceptualization of the challenger party is employed to study their evolution and impact on European party competition. In order to account for the variety of European challenger parties, a large N approach is adopted, analysing 97 elections in 24 countries from 2000 to 2016 and offering a comparison between Western European and Central and Eastern European patterns of competition. This research provides an original definition of the challenger party concept based on party system properties. In this respect, a challenger party is defined as an actor challenging the equilibria of its national party system by i) politicizing neglected issues (nicheness), ii) taking an extreme stance on the left–right continuum (positional extremism), or iii) contesting the rules and norms regulating the party system by employing an anti-establishment strategy (antiestablishmentantagonism). Different bundles of challenger party attributes lead to an empirical identification of four distinct clusters: niche challenger, anti-establishment challenger, purifier challenger, and full-fledged challenger parties. I provide evidence regarding several features of within-cluster homogeneity, showing how these challenger clusters have several commonalities in terms of origin and evolution. In parallel, I show how the impact of challengers on integrated parties varies greatly on the basis of their degree of challengerness, a measure that reflects the intensity of the multidimensional challenge that these parties bring to their party systems. In this respect, integrated parties are more likely to mimic the issue profiles of their challenger competitors when the latter challenge the system through a multidimensional strategy (i.e. high degree of challengerness). Despite this converging tendency on issues, party competition appears to increases the distance between integrated and challenger parties in terms of their anti-establishment strategies. This acute diverging trend underscores the deepening of new forms of polarization within European party systems. In this respect, (anti-)anti-establishment conflict appears as a new line of division increasing the temperature of the party system around the polar distinction between challenger and integrated parties.