sentences:  The Centrists trace their history to the major centrist and Christian-democratic political parties in the Fourth and Fifth Republics.The parties maintained a separate existence from the Gaullist parties in the early years of the Fifth Republic primarily because of de Gaulle's strong opposition to European integration.However the major centrist party, the Union for French Democracy (UDF), began to lose importance after UDF leader Valéry Giscard was defeated by François Mitterrand in the 1981 presidential election and as the Gaullist Rally for the Republic (RPR) become more pro-European during the 1980s and 1990s.