Neosocialism

During the 1930s, the faction gradually distanced itself from revolutionary Marxism and reformist socialism while stopping short of merging into the traditional class-collaborative movement represented by the Radical Party.

In the wake of the Great Depression, a group of parliamentary deputies led by Henri de Man in Belgium (the leader of the Belgian Labour Party's right-wing, and founder of the ideology of planisme, i.e. planism, referring to economic planning) and in France by Marcel Déat and Pierre Renaudel (leader of the SFIO's right wing), René Belin of the General Confederation of Labour, the Young Turk current of the Radical-Socialist Party (Pierre Mendès-France) argued that the unprecedented scale of the global economic crisis, and the sudden success of national-populist parties across Europe, meant that time had run out for socialists to slowly pursue either of the traditional stances of the parliamentary left: gradual, progressive reformism or Marxist-inspired popular revolution.

Instead, influenced by Henri de Man's planism, they promoted a "constructive revolution" headed by the state, where a democratic mandate would be sought to develop technocracy and a planned economy.

[citation needed] On the other hand, Henri de Man's planism influenced the left-wing of the progressive-centrist Radical-Socialist Party, known as Young Turks (among them Pierre Mendès-France).

After 1936 many evolved toward a form of participatory and nationalistic socialism which led them to join with the reactionary right and support the collaborationist Vichy regime during World War II.