Heading the party's Vizcayan section,[3] he advanced to the leadership position upon the arrest of the first general secretary, Antonio García Quejido, in January 1925.

Inheriting a politically divided party, Bullejos attempted to unify the disparate factions, achieving greater unity in Madrid but having less success with the PCE-affiliated FCC-B in Barcelona.

In his absence, Codovilla arranged a new vote which settled the matter and completely denounced Bullejos and the others, who were then expelled from the PCE in October.

Following his expulsion from the PCE and Comintern, José Bullejos joined the Spanish Socialist Workers' Party (PSOE).

With the end of the civil war and the defeat of the Second Republic by the forces of Francisco Franco he fled to Mexico.