PARIS — Marine Le Pen, the far-right French presidential candidate, said on Saturday that she would name a former rival and fellow Euroskeptic as her prime minister if elected, in a new effort to broaden her appeal and defeat her centrist opponent, Emmanuel Macron, in the second round of the country’s elections on May 7.

Ms. Le Pen said she had reached an agreement with Nicolas Dupont-Aignan, a right-wing politician who shares her distrust of the European Union and globalization and who gathered 4.7 percent of the vote, or nearly 1.7 million ballots, in the election’s first round. Ms. Le Pen gathered 21.3 percent.

Ms. Le Pen, sitting with Mr. Dupont-Aignan at a news conference in Paris, praised him as a “patriot” and said that together they would present a “common project” to help them “claim the patriotic and republican victory that our country needs.”

“We must wrest our country from finance, from submission, from the great whirlwind of globalization that will carry us away if we confront it without knowing how to protect ourselves,” she said.