The emergence of social media raises new questions concerning the relationship between journalists and politicians and between news media and politics. The increasingly complex media milieu, in which the boundaries between media producers and audiences become partly dissolved, calls for new theoretical approaches in the study of journalism. This article reassesses central theoretical arguments about the relationship between journalism, sources, politics and democracy. Drawing on a pilot study of the printed press, it explores the increased social media use among politicians in Sweden and its implications for political journalism. The article suggests that power relations between journalism and politics can be fruitfully explored from the perspective of mediatized interdependency, a perspective that acknowledges that journalists and politicians have become both actors and sources through mutual interaction in online spaces. Furthermore, it argues that social media use has expanded journalism's interest in the private life of politicians, thereby contributing to a de-politicization of politics.