During every crisis of representative democracy, there is a surge of demands for more direct forms of participation, especially from new political parties. Whether it is the populist movement at the end of the 19th century in the US or the Five Star Movement in current-day Italy -- discontent with the representative system increases demands for alternative institutions. But what explains the position of the main actors in the formulation of these demands? We ask why political parties call for and/or support direct democracy. We provide two major motivations: ideology and strategy. Analyzing party manifestos of European parties from 1946 onward using a novel machine learning classifier, we show how ideological motivations seem to account for most variation in party positions towards direct democracy. These results contribute to the literature on institutional origins and sheds light on the motivation of a central political actor, parties, when it comes to the introduction of direct democratic institutions.