Institutional incentives for strategic voting and party system change in Portugal

Looking more closely at the way people form expectations about the possible outcome of the election in their electoral district I will provide evidence for the first time that strategic voting can be observed and predicted even in PR systems with large districts magnitudes, such as in Portugal. Employing district-level data from 19752002 I estimate that a party, who is expected to win no seat, will be strategically deserted on average by about 3 per cent of the voters. This number does systematically vary with the district magnitude of each district. Nevertheless even in Portugal's largest electoral district, Lisbon, strategic voting can be observed to have a systematic impact on parties vote shares. Moreover there is evidence that strategic voting can partly account for the majoritarian trend that can be observed within the Portuguese party system.