Mayor Ana Botella, who succeeded Alberto Ruiz-Gallardón early into his term in December 2011, had declined re-election in September 2014.

The collapse in the PP vote and the loss of its absolute majority allowed Carmena to gain power through an alliance with the Spanish Socialist Workers' Party (PSOE), resulting in the first left-wing government in the city since 1989.

The newcomer liberal Citizens (Spanish: Ciudadanos) party also entered the City Council for the first time, collecting votes disenchanted with the PP and replacing Union, Progress and Democracy (UPyD) as the main centrist local force.

[2] Voting for the local assembly was on the basis of universal suffrage, which comprised all nationals over 18 years of age, registered and residing in the municipality of Madrid and in full enjoyment of their political rights, as well as resident non-national European citizens and those whose country of origin allowed Spanish nationals to vote in their own elections by virtue of a treaty.

[1][2] Councillors were allocated to municipal councils based on the following scale: The mayor was indirectly elected by the plenary assembly.

The latter, visibly surprised, counterattacked responding that Aguirre was acting arrogantly and contemptuous to others and accusing her of allowing corruption to spread during her tenure as President of Madrid.

[10] In the last days of the campaign, especially following her debate with Aguirre, several celebrities such as actors Pilar Bardem, Carlos Bardem, Loles León, Goya Toledo, Paco León, playwright Cristina Rota, lawyer and former politician Cristina Almeida and journalist Ernesto Ekaizer expressed their support for Carmena's candidacy, with actress Eva Hache going on to say through the Twitter social network that "I don't know if we are Manuela but surely we are not the other [in reference to Aguirre].