It was 9 p.m. on Sunday when left-wing leader Jean-Luc Mélenchon held a press conference to celebrate his quasi-victory in the first round of the general election. The New Popular Front he had set up 20 days earlier — a coalition of vestigial leftist parties, the communists, the socialists, the Greens, robustly backed by his own extremist group, La France Insoumise, or France Unbowed — was coming second in the race, with 27.99 percent of the vote nation-wide.