NICE, France — France’s far-right presidential candidate, Marine Le Pen, came out swinging against her centrist opponent, Emmanuel Macron, on Thursday night, depicting him as an unpatriotic out-of-touch banker in a tough, slashing speech intended to fuel her uphill bid for an upset in the May 7 runoff.

The showdown is a clash of opposites, a contest between her superheated anti-immigrant, xenophobic language and his cool and lofty formulas for restoring France’s economy while upholding its global alliances. On Thursday, to an adoring crowd of thousands in Nice, Ms. Le Pen made the most of that contrast in her first speech since finishing second in the first round of voting on Sunday.

Mr. Macron, a former economy minister and banker, was a “globalist,” an “immigrationist” and someone who is capable of cutting himself off from the country, Ms. Le Pen roared to flag-waving supporters at a vast auditorium at the edge of town. The boos for Mr. Macron lasted for minutes.

Still, the odds are sharply against her. Polls show Ms. Le Pen trailing by more than 20 percent. But in the last few days, she has gained some momentum while Mr. Macron has stumbled since the first round.