Tellingly, French politicians across the ideological spectrum invoke the names of both Jaurès and de Gaulle — a measure of their greatness, of course, but also the smallness of their descendants. Not only have Mr. Hollande and former President Nicolas Sarkozy engaged in this form of hijacking, but so, too, has Marine Le Pen of the National Front (F.N.), who dismissed the Gaullist Union for a Popular Movement (U.M.P.) for “betraying” its founder’s vision for France, all the while comparing herself to the general who, like her, was distrusted by the Left and Right. At the same time, Steeve Briois, F.N. mayor of Hénin-Beaumont, cited Jaurès during his campaign, while for Ms. Le Pen’s second-in-command (and partner), Louis Aliot, Jaurès would now vote for the F.N.