The battle inside the PSOE for control of its organisational structures was waged on behalf of the reformist wing largely by one man, Ramon Lamoneda. Although as general secretary he had been in control of the PSOE's national executive since the summer of 1936, it was with the appointment of Juan Negrín as Republican premier in May 1937 that Lamoneda came to real political prominence. The PSOE's general secretary was to become the crucial link whereby the PSOE hierarchy came to be identified with the Negrín government at whose centre was a reflection of the parliamentary reformism and inter-class alliance championed for so long by Indalecio Prieto.

As the socialist leaders of state and party respectively, Negrin and Lamoneda had similarly severe views on discipline. Both tended towards the authoritarian, which, while a certain concentration of power was essential in a wartime situation, would in the future tend to alienate their fellow socialists. Lamoneda's extremely rational and pragmatic approach, above all to the increasingly thorny issue of relations between the socialist and communist grass roots, would lead his critics to accuse him of being cold, callous and impervious to the hardships of the socialist rank and file.