Original: In order to exist between the Communist Party, leading the left, and the Gaullist Party, leading the country, the SFIO, Radicals, and left-wing republican groups created the Federation of the Democratic and Socialist Left under Mitterrand's leadership.
Simplified: In order to exist between the Communist Party, leading the left, and the Gaullist Party, leading the country, the SFIO, Radicals, and left wing republican groups created the Federation of the Democratic and Socialist Left under Mitterrand's leadership.