Dynamic party system fragmentation

Although most new democracies have a relatively high level of party system fragmentation, most of them experience a reduction in the number of parties over time. In Brazil, the number of parties has increased significantly since the first election after the 1988 constitution, even though no significant institutional change has taken place. Existing explanations of fragmentation cannot account for this fact. We argue that the increase in fragmentation observed in Brazil is endogenous: it is not caused by the creation of new parties, but by the combination of institutions that, paradoxically, incentivizes marginal candidates to join relatively small parties in order to improve their chances of success. We use data from seven elections at the national and state levels to show that marginal candidates are more likely to change to smaller parties between elections and that those who do it are more likely to get elected than those who do not.