Existing literature posits that, in low-information settings, voters base their choices on candidates’ looks. This often favours disproportionately right-wing politicians who happen to enjoy an appearance premium. We argue that this is endogenous to politicians self-selecting into parties. We show that the Republican party is a more homogenous looking party and individuals most similar to the ‘ideal’ Republican stereotype benefit from an advantage in open-seat elections, compared to Democrats. The electoral premium enjoyed by Republicans is due to a greater similarity between its members. As a result, Republican voters spot more easily ‘in-group’ members and use this similarity as a cue for their choices in low-information settings. Additionally, we predict that the winner in the Republican primaries is the one looking most like the `average’ Republican, whereas this is not the case for Democrats. Using machine learning analysis of portraits of winners and runner-ups for the US Congress and Senate we confirm these predictions.