Voter turnout and government's legitimate mandate

The paper studies a group-mobilization model of costly voting in which citizens care about the legitimate mandate of the government formed by the winning group. This, as a function of the electorate's voting behavior, depends on both the margin of victory and the total turnout rate. Citizens prefer a high mandate when their own group forms the government but a low one if the government is formed by an opposing group. As such, the eventual losing group faces a trade-off: a higher participation from its members decreases the margin of victory but increases the total turnout. In equilibrium, a second fundamental trade-off arises, which overturns the supposed positive relationship between turnout and mandate: as the total turnout becomes more important for the government's mandate, the first decreases but the second strengthens. The key mechanism at play is a shift in the relative participation of the two groups, which favors the majority and raises its margin of victory, thus yielding a bandwagon effect. The implications for the evolution of turnout and the occurrence of election boycotts are discussed.