French political party. The oldest of France's political parties, it was founded in 1901 but originated in the 1870s in the reformist wing of the French Republican Party, known as the Radicals, led by Georges Clemenceau. Traditionally a centrist party, it was most prominent in the Third Republic and Fourth Republic. In the 1920s and '30s it joined coalition governments with the French Socialist Party. After 1945 it led other centrist groups to form politically important coalitions. By the late 20th century, however, it was only a minor party. In 1998 it renamed itself the Radical Party of the Left