LE BOURGET, France (AP) — Young supporters wore his name on their backs like a soccer star’s, above the number 27. They sang about brass bands and revolution. Many had spent the fall protesting or blockading their schools.

Then in walked Jean-Luc Mélenchon: 75 years old, on his fourth presidential run and old enough to be their grandfather.

“I have only one sensible thing to propose,” he told 20,000 supporters in a vast hall north of Paris on Saturday. “Everything must change.”

The septuagenarian may never get another chance. Three presidential bids have ended short of the runoff. In 2022, just 421,308 votes kept him out. Now, riding a surge in support, he is eyeing a winner-take-all showdown with far-right front-runner Marine Le Pen.

The bespectacled, booming and seemingly tireless leftist wants more than the presidency.…