Are differences in issue‐specific knowledge associated with different candidate preferences, as would be expected if voters are judging candidates and their policy commitments on the basis of essential contextual knowledge they receive from the media? By utilizing a bias‐sensitive method of measuring politically relevant knowledge—on economic, foreign policy, and environmental issues—we were able to identify candidate‐selection effects of policy‐specific information. The study also offers new evidence on how psychological traits affect political thinking within a partisan group, whereas most research has focused on psychological asymmetries across ideological and partisan groups. Based on previous research, we expected Sanders supporters and supporters of other “anti‐establishment” candidates to have less accurate knowledge on these issues than Biden (and other establishment candidate) supporters, as the demographic groups that differentially supported Sanders tend to have lower levels of political knowledge. Instead, Sanders and anti‐establishment candidate supporters were found to be more knowledgeable on these issues. We also found psychological asymmetries among Democrats and Democrat‐leaning Independents, which were associated with candidate preference. Overall, issue‐specific political knowledge was found to be an important predictor of vote choice.