Today’s election campaigns are heavily data-driven. Despite the numerous skeptical voices questioning the compatibility of specific campaigning practices with fundamental principles of liberal democracies, there has to date been little comprehensive work in this area from the perspective of normative democratic theory. Our article addresses this gap by drawing on recent research on the normative theory of political parties in the field of deliberative democratic theory. The deliberative theories of democracy proposed by Habermas and Rawls contain structural elements of a normative theory of the political party: the special status of political parties as mediators between background culture and the political forum, between the political system and the public sphere, and between the individual and the state, confers on them a central position as actors in in the public use of reason and deliberation.We argue in this article for a view of digital campaigning as a policy of democracy promotion and for the proposition that, alongside other actors, political parties have a special responsibility in this regard. We point to the implications for the evaluation and design of digital political microtargeting that arise from the application of deliberative principles to political parties and consider the need they reveal for the ongoing development of detailed, nuanced normative theories of democracy.