We investigate the partisan foundations of political legitimacy. We argue that the goals parties pursue shape their supporters' views about the political system via the messages they communicate about the desirability of the political system. Combining public opinion survey data collected in 15 democracies with data on the goal orientations and policy positions of 116 political parties, we find that office-seeking parties take more positive positions toward the status quo of the political regime than policy-seeking parties. Moreover, we find that these positions have consequences. Specifically, supporters of parties with more positive positions toward the system report systematically higher levels of support than supporters of parties that communicate more negative views. Taken together, these findings suggest that political parties play an active role in shaping citizens' views of the political system and that office-seeking parties in particular mobilize consent among citizens in contemporary democracies. © European Consortium for Political Research.