While the recent rise of protectionism in the US has spurred research on the economic and electoral effects of tariffs, we know less about the impact of political institutions on politicians’ response to growing protectionism abroad. In this paper, we examine to what extent electoral rules shape legislative responses to the trade wars. Building on theories of electoral rules and trade policy, our empirical strategy leverages the interaction of the international trade policy shock and within-country variation in electoral institutions. We study legislative votes on trade in Switzerland 2003-2023, a small open economy that uses a proportional electoral system with districts of varying magnitude. This setting enables us aim to conduct a difference-in-difference analysis to examine how district magnitude shapes politicians’ legislative response to the onset of the trade war. We find that politicians become more protectionist in larger electoral districts. These preliminary results are hard to reconcile with some of the standard models in the literature.