Collusion Between Mainstream Parties and Anti-Establishment Parties’ Success

It is a common wisdom that outsider parties may take advantage of mainstream parties colluding with each other, either by participating in the same government coalition or significantly reducing their ideological distance. This reinforces populist or anti-establishment leaders claim to represent the only real alternative To traditional politics. The same argument can be presented in spatial terms: the more mainstream parties get closer to each other, the more political space is available for outsider challengers. Although very diffused, such argument has never been empirically tested. This is what we do in this paper. We have assembled an original dataset including governmental coalitions in 17 Western European countries since 1980. In order to test the ‘collusion hypothesis’, we use coalitional formulas as an independent variable to explain the electoral success of outsider parties. Our results show that there is no direct relation between grand coalition formulas and the rise of populist anti-establishment parties.