The lesser evil: executive accountability with partisan supporters

We develop a model of electoral accountability with primaries. Prior to the general election, the supporters of each of two parties decide which candidates to nominate. We show that supporters suffer from a fundamental tension: while they want politicians who will faithfully implement the party's agenda in office, they need politicians who can win elections. Accountability to supporters fails when supporters fear that by punishing or rewarding their incumbent for her loyalty or lack thereof, they unintentionally increase the electoral prospects of the opposing party. Therefore, accountability decreases with the importance that supporters assign to the elections, and it breaks down in two cases. First, a popular incumbent safely defects as she knows she will be re-nominated. Second, an unpopular incumbent defects because she knows she will be dismissed even if she follows the party line. These behaviors are labeled impunity and damnation, respectively, and are illustrated with case studies.