The congress was called after the PSOE suffered its worst defeat since the Spanish transition to democracy in the general election held on 20 November 2011.

Previous secretary-general José Luis Rodríguez Zapatero had announced in April the same year he would not stand for election to a third term as Prime Minister of Spain, announcing his intention to step down as party leader after a successor had been elected.

[2][3] The key dates are listed below (all times are CET):[4] The individuals in this section were the subject of speculation about their possible candidacy, but publicly denied or recanted interest in running: Candidates seeking to run were required to collect the endorsements of at least 10% of federal committee members and of between 20% and 30% of congress delegates.

The highest percentage figure in each polling survey is displayed in bold, and the background shaded in the candidate's colour.

Polls show data gathered among PSOE voters/supporters as well as Spanish voters as a whole, but not among delegates, who were the ones ultimately entitled to vote in the congress election.