• Socialist Militant Marceau Pivert, 1895
• Prime Minister of France Paul Ramadier, 1888

 

Active in the Syndicat National des Instituteurs (SNI), a staunch supporter of laïcité and a pacifist after service in World War I, Pivert joined the Socialist Party (PS) and then the French section of the Workers' International (SFIO) wing under Léon Blum (the section of the Party that had refused in 1920 adherence to the Comintern, as opposed to the new French Communist Party, PCF).

In the early 1930s, Pivert grouped the most left wing members of the SFIO in his Gauche Révolutionnaire ("Revolutionary Left") tendency, to which Daniel Guérin was a member, one which opened itself to Trotskyism, initiating entryism as a tactic for the latter.

In 1936, when Blum formed the Popular Front government, he was pressured by Pivert to reject Capitalism. Witness to the spontaneous strikes around the country, Blum refused to allow for revolutionary conditions to arise. Pivert then wrote his best known article, published on 27 May, headlined Tout est possible! ("Everything Is Possible"), alluding to a social revolution (although never to a socialist one). However, he was contradicted by the communist press organ L'Humanité (the PCF was a backer of the Blum government). The communist editorial read: Non! Tout n'est pas possible! ("No! Not Everything Is Possible!"). In consequence, Pivert cut off links with the government, writing to Blum that "I will not accept capitulation in front of Capitalism and the banks".

The Gauche Révolutionnaire left the SFIO to establish the Workers and Peasants' Socialist Party (Parti Socialiste Ouvrier et Paysan, PSOP), which had a hard time finding a place in between the Socialists and the Stalinists. In fact, its ideology fluctuated from Marxist orthodoxy to a radical version of Reformism. The PSOP was part of the International Revolutionary Marxist Center. In 1940, the PSOP was outlawed after the fall of France to Nazi Germany, through the orders of Vichy government leader Philippe Pétain.

Pivert exiled himself to Mexico, and supported the French Resistance. Returned to France after World War II, he saw the PSOP divided between the wing that joined the PCF (which had acquired prestige after its active contribution to the Resistance), and the one that joined the SFIO - he himself opted for the latter.

He became more moderate inside the SFIO, and his audience was curtailed. Pivert was regularly elected to the party leadership, but nonetheless stood for Algeria's independence and was hostile to the creation of a European Defense Community (contrary to the party line). He antagonized the SFIO further after taking part in a delegation that visited the Soviet Union, and was voted out of his central position. According to some, Pivert had projected joining the new Parti Socialiste Autonome (PSA) created by Édouard Depreux and Alain Savary, but died before being able to carry out the merger. However, most of his followers in the SFIO entered the PSA later in 1958.