The right-wing, led by Pierre Mauroy and Gaston Defferre, was composed of some local elects who made alliances with the centrist parties, whereas the left-wing CERES faction led by Jean-Pierre Chevènement wanted to accelerate the process of an alliance with the French Communist Party (PCF).
The general principle of the "Union of the Left" was adopted, but the alliance with centrist parties was tolerated in some local assemblies.
Mitterrand and the CIR, which joined the PS in Epinay, advocated immediate negotiations with the PCF in order to write a common election programme.
The will to overthrow Savary and Mollet's group from the leadership of the party permitted the birth of a broad coalition between the Mitterrand, Defferre, Mauroy and Chevènement factions.
Mitterrand became the new PS first secretary and in the following year signed the Common Programme with the Communist Party and the Movement of the Radical-Socialist Left.