Since the 2013 leadership election of the Democratic Party (PD) in which Matteo Renzi (a centrist) was elected secretary, the party was riven by an internal struggle between Renzi's large majority (composed of "renziani", assorted centrists and moderate social democrats) and the left-wing factions which were very critical of Renzi, his government (2014–2016) and his proposed constitutional reform, which was finally voted down in a constitutional referendum in December 2016.