Le Pen's loss to centrist Emmanuel Macron still gave her a historic number of votes, reflecting the changing image of her once-pariah National Front party from fringe force to a political heavyweight.
Always a fighter defying the odds, the ambitious Le Pen set a new challenge for herself: "a profound reformation of our movement to constitute a new political force."
The National Front's interim president, named while Le Pen campaigned for Sunday's runoff, said the changes include giving the party a new name.
Changing the name was discussed at the height of Le Pen's efforts to scrub the party image and remove traces of racism and anti-Semitism that scared away potential backers. But party stalwarts saw the change as too radical.
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A new name would help Le Pen distance herself from the old guard -- including her father, party founder Jean-Marie, who was kicked out under his daughter's image revamping.
The party's new look won't come about before the parliamentary elections on June 11 and 18.
The notion that a new movement under Le Pen could lead to political alliances and entice new voters poses a challenge to Macron, who said during his victory speech that the anger and despair of far-right voters must be acknowledged. He faces his own challenge finding a parliamentary majority.
The message crossed French borders: Germany's foreign minister, Sigmar Gabriel, laced his welcome for Macron with a warning to the French: "If he fails, in five years Mrs. Le Pen will be president and the European project will go to the dogs."
Le Pen, who came third in the 2012 presidential election, has spent years planting a grassroots structure for her party.
In 2014, the National Front won 11 towns in municipal elections, and her party performed better than any in France in elections for the European Parliament, where she co- presides over a far-right group.
Now she wants a wider spectrum of voters, "those who choose France, defend its independence, its freedom, its prosperity, its security, its identity and its social model." "I will be at the head of this combat," she said.
"It is this great choice ... That will be submitted to the French in legislative elections," she said in her concession speech.