What is the role of elite-level inter-party strategies in promoting or reducing negative affective evaluations of citizens? This article explores this puzzle by focusing on the decision of mainstream parties to exclude or cooperate with populist radical right-wing parties (PRRPs) in Western European countries. The analysis is based on CSES cross-national data and the LISS Dutch panel data merged with the record on whether PRRPs are subject to a cordon sanitaire or (in)formally cooperate with mainstream parties in a government coalition. The findings suggest that political exclusion fuels loathing for PRRPs among mainstream party supporters, while cooperation reduces dislike of PRRPs both among supporters of PRRP coalition partners and left-wing voters. Distinguishing between informal and formal coalitions, the cross-national data shows that only formal cooperation has a significant effect. However, the longitudinal Dutch data shows a temporary decrease of dislike also during informal cooperation.