Coalition Government and Party System Change: Explaining the Rise of Regional Political Parties in India

Why do party systems in longstanding democracies sometimes experience sudden change? Neither sociological nor institutional explanations can account for the swift increase in support for regional political parties in India in the 1990s. Instead, the shift from single-party majority to coalition government explains the rise of regional parties. The advent of coalition government increased the incentives associated with joining and establishing regional parties, prompting many already popular politicians to leave their national parties and take their supporters with them as they formed new regional parties in the 1990s. This finding reverses the causal arrow that usually links party systems and coalition government and illustrates how noninstitutional elements of the political context can determine elite incentives and thereby shape party systems.