This article argues that digital media are introducing a new grassroots-based mode of ‘citizen-initiated campaigning’ (CIC) that challenges the dominant professionalized model of campaign management by devolving power over core tasks to the grassroots. After defining the practice through reference to the 2008 campaign of Barack Obama and online parties literature, we devise a measure of CIC that is applied to UK parties in the 2010 election. Our findings show that CIC is emerging outside the U.S. and adoption is associated with major party status, although it may be of particular appeal to political actors facing a resource deficit. The conclusions focus on the implications of CIC for new forms of party membership, indirect voter mobilization and the contextual factors influencing this new model of campaigning.