When the immigration issue has been strongly politicized, prejudice toward minority out-groups can be profoundly imbued with politics, to the point that citizen responses to partisan cues about immigrants tend to operate on the basis of a ‘political sympathy/antipathy bias’. This article demonstrates that there is a direct causal relation between the nature (i.e. contents and sources) of political communication over immigrants and voters' responses. Drawing on an experimental design based on ITANES (Italian National Election Studies) 2018 election survey data, it isolates the effect that the voters' ideology and party alignments, as well as the partisan source of a message, exert on manifestations of ethnic prejudice, operationalized as the refusal to accept a plausibile and counter-stereotypical statement about immigrants. It concludes that even a mere symbolic change in communication by those party actors (i.e. the League) which ‘own’ the issue would suffice to attenuate hostility toward out-groups, to the extent that it results from sustained partisan rhetoric and mobilization.