The main theories explaining electoral backlash against immigration give centrality to citizens’ cultural, economic, and security concerns. We test these predictions in Switzerland, which opened its labor market to neighboring countries in the 2000s. Using a difference-in-differences design, we document that immigration to Swiss border municipalities increased substantially after the borders opened, followed by a more than six percentage point (29%) increase in support for anti-immigrant parties. However, we find no adverse effects on citizens’ employment and wages nor on their subjective perceptions of economic, cultural, or security threats. Instead, we describe how far-right parties introduced novel threats to increase hostility toward immigrants. Our evidence demonstrates how elite rhetoric targeted border municipalities and had the greatest effects on voters vulnerable to political persuasion. Together, these findings emphasize the role that elites may play in driving anti-immigrant votes.