The survival and termination of party mergers in Europe

Abstract

Why do constituent parties that participated in a party merger that was intended to be permanent decide to leave the merger to re‐enter party competition separately? To address this question, merger termination is conceptualised in this article as an instance of new party formation, coalition termination and institutionalisation failure. Building on this conceptualisation, three sets of factors are presented that account for which mergers are likely to be terminated by constituent parties and which are not. To test these three sets of hypotheses, a mixed‐methods design is used. First, survival analysis is applied to a new dataset on the performance of mergers in 21 European democracies during the postwar period. The findings support hypotheses derived from a conception of merger termination as new party formation: pre‐ and post‐merger legislative performance significantly affect the probability of merger termination. Furthermore, the institutionalisation of constituent parties helps to sustain mergers if the latter already built trust in pre‐merger cooperation, in line with the conception of merger termination as institutionalisation failure. Two theory‐confirming case studies are then analysed: one case of merger survival and the other of termination. These case studies substantiate the working of the significant variables identified in the large‐N analysis that drove the selection of case studies. They also reveal how mediating factors difficult to capture in large‐N designs help to account for why factors that – theoretically – should have complicated the working of the ‘survival case’, and should have been beneficial to the ‘termination case’, did not generate the expected effects.

Party survival in parliament: Explaining party durability in lower‐house parliaments

“…While mergers and splits can be a strategic choice by a party elite (Bolleyer ; Bolleyer et al. , ; Ibenskas ), I do not limit the analysis to a specific reason for party failure. Modelling party survival in this simple and straightforward way allows for a broad understanding of parties’ ability to survive as independent institutions within the lower house legislature.…”

“…Bolleyer et al. () find that electoral threshold is not associated with a longer duration of the termination of a party merger. Thus, we should expect that high legal threshold will be negatively associated with duration of party survival in parliament.…”

“…Parties may disappear from parliament for various reasons, including merging with another party, splitting into two or more parties or simply lacking the votes in the next election to win seats in parliament. While mergers and splits can be a strategic choice by a party elite (Bolleyer 2013;Bolleyer et al 2016Bolleyer et al , 2018Ibenskas 2016), I do not limit the analysis to a specific reason for party failure. Modelling party survival in this simple and straightforward way allows for a broad understanding of parties' ability to survive as independent institutions within the lower house legislature.…”

“…; Spoon ), causes of disappearing (e.g., Bolleyer et al. ; Mershon & Shvetsova ), or specific regions (e.g., Beyens et al. ; Bianco et al.…”

“…Despite the political importance of parties, the research on party survival in parliament mainly focuses on small parties (e.g., Dinas et al 2015;Spoon 2011), causes of disappearing (e.g., Bolleyer et al 2016;Mershon & Shvetsova 2013), or specific regions (e.g., Beyens et al 2016;Bianco et al 2014). Van de Wardt et al (2017) find that electoral competition between similar parties increases the probability that a party will exit parliament.…”