Everyday partisans evaluate policies partly by following partisan cues, fomenting polarization. However, there is debate over the influence of partisan cues in “real-world,” nonlaboratory contexts. An experiment with a real climate change initiative in the 2016 Washington State election tested whether partisan cues influenced climate policy polarization. In a primary study, 504 prospective voters were randomly assigned to view veridical policy endorsements by partisan elites; this study was followed by a preregistered conceptual replication ( N = 1,178). Democrats supported the climate policy more than Republicans. But this difference was greater when Democrats endorsed the policy (with Republican opposition) than when Republicans endorsed the policy (with Democratic opposition). Neither knowledge nor belief in climate change reduced these polarizing effects, and greater policy knowledge was associated with increased polarization. Further, the effect of partisan cues on normative perceptions mediated the effect of partisan cues on policy support.