Containment measures and electoral system choice

Abstract This chapter presents our neo-Rokkanian account of electoral system choice. We argue that once an electoral threat emerges, established parties can respond in two ways. If established parties can resort to partisan districting or electoral alliances, they can contain the electoral threat, but these measures lead to growing seat-vote distortions. Moreover, given that these containment measures are primarily effective in majoritarian representation (MR) systems, established parties retain their attachment to MR, whereas parties disadvantaged by the resulting biases favour the adoption of proportional representation (PR). In contrast, if established parties cannot resort to partisan districting and electoral alliances, they support the adoption of PR. In this response, seat-vote distortions are not significant enough to contain the insurgent party. Partisan biases might even turn against the established parties. Consequently, the established parties opt for a more inclusive electoral system that allows them to limit their seat losses in the face of an electoral threat.