A short-term obstacle to united political action to fight climate change in various countries is opposition to pro-environmental policies among conservatives. Three preregistered studies test the hypothesis that because conservatives have a higher need for closure than liberals (Hypothesis 1), framing pro-environmental policies in a way that appeals to the need for closure, reduces conservatives’ opposition to these policies (Hypothesis 2). Study 1 confirms Hypothesis 1. Next, two studies test Hypothesis 2 and find that conservatives are less opposed to pro-environmental policies proposed by a politician (Study 2) or an NGO (Study 3) if these policies are framed in a way that appeals to the need for closure, while the opposite is the case for liberals. Across these two studies, we also test the underlying process but find no evidence for the idea that differences in need for closure mediate the effect (Hypothesis 3a). Instead, the effect is primarily driven by inferences about group membership and ingroup bias (Hypothesis 3b, non-preregistered). That is, these data suggest that framing policies to appeal to closure needs reduces conservatives’ opposition because they infer that the policy is proposed by a fellow conservative.