How do party cues and policy information affect citizens’ political opinions? In direct democratic settings, this question is particularly relevant. Direct democratic campaigns are information-rich events which offer citizens the opportunity to learn detailed information about a policy. At the same time parties try to influence citizens’ decision procedure by publishing their own positions on the issue. The current debate on whether “party” or “policy” has more impact on political opinions has not yet yielded conclusive results. We examine the effect of policy arguments and party cues on vote intention in two Swiss referendum votes using panel survey data. To the simple dichotomous question of “party cues or policy information” we add an additional twist in asking how party cues affect the processing of policy information through processes of motivated reasoning. We find first that both, policy arguments and party cues, have an independent effect on vote intention. However, in a second part of the analysis, we find strong evidence for partisan-biased processing of policy arguments – that is, voters tend to align their arguments with their preferred party’s position. Our conclusions with regard to the democratic quality of these vote decisions are therefore ambivalent.