Majoritarian Parties in Multi-Party Parliaments

Westminster-derived parliamentary systems are typically associated with two party systems and single party majority government. However, party system fragmentation in several of these systems has compelled majoritarian political parties that are accustomed to single party majority government to adapt to prolonged periods of minority and/or coalition government. If we assume that parties are unitary rational actors operating within institutional constraints,1 then we can predict that majoritarian parties will respond to environmental change by adapting their strategies so that they can still win office. In a newly fragmented party system, a majoritarian party will enter strategic executive or legislative coalitions in order to form a government. The party will make any tactical adjustments necessary to maintain a collaborative relationship with the minimum number of required support parties, while retaining a sufficiently distinct brand to maximise its vote share. Because the partys organisational structure, selection of personnel and policy positions have all been adopted over time with the goal of single party majority government in mind and changing any of these elements is costly, in the absence of clear evidence that party-system fragmentation is a long-term phenomenon, party strategy will revert to the pursuit of singl