The was a socialist

Socialism

Socialism is an economic system characterized by social ownership of the means of production and cooperative management of the economy; or a political philosophy advocating such a system. "Social ownership" may refer to any one of, or a combination of, the following: cooperative enterprises,...

 and republican

Republicanism

Republicanism is the ideology of governing a nation as a republic, where the head of state is appointed by means other than heredity, often elections. The exact meaning of republicanism varies depending on the cultural and historical context...

 party in France

France

The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

 led by François Mitterrand

François Mitterrand

François Maurice Adrien Marie Mitterrand was the 21st President of the French Republic and ex officio Co-Prince of Andorra, serving from 1981 until 1995. He is the longest-serving President of France and, as leader of the Socialist Party, the only figure from the left so far elected President...

. The CIR, founded in 1964 transformed from a loosely organized club to a formal political party by the time of Mitterrand's candidacy in the 1965 election

French presidential election, 1965

The 1965 French presidential election was the first presidential election by direct universal suffrage of the Fifth Republic. It was also the first presidential election by direct universal suffrage since the Second Republic in 1848. It was won by incumbent president Charles de Gaulle who resigned...

. Roughly at the same time, the CIR played an important role in the foundation of the Federation of the Democratic and Socialist Left

Federation of the Democratic and Socialist Left

The Federation of the Democratic and Socialist Left was a conglomerate of French left-wing non-Communist forces. It was founded to support François Mitterrand's candidature at the 1965 presidential election and to couter-balance the Communist preponderance over the French left...

 (FGDS), which ended with the FGDS' landslide defeat to the Gaullists in the 1968 election

French legislative election, 1968

- National Assembly by Parliamentary Group:...

.

The CIR dissolved itself into the Socialist Party at the Épinay Congress

Epinay Congress

The Epinay Congress was the third national congress of the French Socialist Party , which took place on 11, 12 and 13 June 1971, in the town of Épinay-sur-Seine, in the northern suburbs of Paris...

 in 1971.