[2] Linked to Christian movements and organizations,[3] he affiliated to the then clandestine PSOE and Unión General de Trabajadores (UGT) in 1972.

[6] Invested again as Mayor of Fuenlabrada, soon after being sworn to office for a second spell he handed in his resignation in order to become Minister of Education and Youth of the first government of the community of Madrid, presided by Joaquín Leguina.

He was one of the members (along José Antonio Pérez Tapias and Juan Antonio Barrio de Penagos) of the Socialist Parliamentary Group in the Congress who decided not to take part in the September 2011 voting for the reform of the Spanish Constitution struck by the PSOE and the People's Party that sought to include (and successfully did so) the principle of "budgetary stability" in the Article 135 of the text.

Nonetheless, de la Rocha became later a member of the 10th Congress of Deputies in July 2014, replacing the vacant seat of Elena Valenciano, elected to the European Parliament.

[12] De la Rocha, who was serving as secretary in the board of trustees of the Fundación Alternativas, announced his intentions to run in the PSOE primaries to select the party challenger to the post of Mayor of Madrid in October 2018.