Born in San Valentín, Fene, on 6 May 1971, next to the shipyard of Astilleros y Talleres del Noroeste (ASTANO), Díaz is a member of a family of renowned trade unionists in Galicia who were strongly involved in anti-Francoist activism.

[5] Díaz joined the Communist Party of Spain (PCE) at an early age,[4] before entering institutional politics in 2003, when she became member of the Ferrol municipal council.

[11] She chose Joaquín Pérez Rey to hold the post of Secretary of State for Labour and Social Economy, making him the effective second-in-command in the Ministry.

[12] As Minister of Labour, Díaz took part in the negotiations that paved the way for the increase of the minimum wage to 950 euros per month, in addition to outlawing employee dismissal for medical leave.

[17] On the same Monday, in a press conference from Montauban, the President of the Government, Pedro Sánchez, also confirmed the succession of the vice-presidency to Díaz, declaring that he had "the highest regard" for her.

In November, Díaz announced her intention to create a political platform to contest in the next Spanish general elections, starting a "listening process" after the Christmas holidays, popularly identified by the media as a "broad front".

In these elections, Sumar obtained 3 deputies out of 61, results valued negatively by the members of the coalition, especially by Izquierda Unida, a party that was left without parliamentary representation as its MEP Manu Pineda lost re-election due to him being placed fourth on the list.

[29][30] Diaz, still a member of the Communist Party of Spain,[31] now avoids declaring herself as one and focus entirely on left-wing voters,[32] although she has praised the regimes of Fidel Castro in Cuba and of Hugo Chávez in Venezuela in the past.

Capitalism has been ever present in all of its diverse and voracious mutations, ready to engulf, corrupt, and disintegrate the very reality that constitutes it, but without ever being able to escape the theories of Marx and the transforming power of this text.

[39] Diaz describes herself as an atheist, but claims meeting Pope Francis, who regularly criticises uncontrolled capitalism, was "the most important encounter" of her life, and the two keep in touch because they "have so much in common.