This paper develops an infinite-horizon, political agency model with a continuum of political districts, in which incumbent politicians can improve their re-election probability by attracting swing voters in key states through strategic trade protection. A unique equilibrium is shown to exist where incumbents build a reputation of protectionism through their policy decisions. We show that strategic trade protection is more likely when protectionist swing voters have a lead over free-trade supporters in states with relatively strong electoral competition that represent a larger proportion of Electoral College votes. US data is used to test the hypothesis that industrial concentration in swing and decisive states is an important determinant of trade protection of that industry. The empirical findings provide support for the theory and highlight an important, and previously overlooked, determinant of trade protection in the US Electoral College.