A lot of scholarly attention has been devoted to political polarization in the American public. One account describes the cleavage as ideological, namely revolving around divergent policy preferences of different partisans. A different explanation holds that party labels are strong heuristics that voters use to adjust their policy preferences to their party. As there is usually a reasonable fit between the partisanship of the policy promoter and the policy goal, it is difficult to discern which is a stronger driver of policy evaluation and opinion formation: partisan cues or ideological preferences? Using an original experiment that includes both policy content and partisan sponsorship as distinct and orthogonal attributes of policy proposals, I test the extent to which Democrats and Republicans are driven by policy preferences and partisan cues. I find that across an array of domains, the content of the policy has virtually no effect on the preferences of different partisans. This holds even on issues pertaining to key ideological divides such as taxation. Instead, I find that partisan cues have major effects on respondents' views on a given policy. The one exception are policies dealing with moral issues – e.g. euthanasia and pornography consumption – which seem to be driven by both policy considerations and partisan cues. Overall, these findings suggest that polarization on policy issues is also an outcome, and not just a cause, of partisanship in the US public sphere.