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 . 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 .