Defeated French presidential candidate Marine Le Pen claimed a "massive" result for the far right in Sunday's presidential run-off against centrist Emmanuel Macron, but said her National Front (FN) party had to undergo major change.
Separately, the FN's deputy leader, Florian Philippot, said the party would alter its name as it sought to transform itself into a "new political force."
But in signs of a possibly wrenching internal debate about the future, Le Pen's powerful niece -- long rumoured to be a potential successor -- said the election result had been somewhat disappointing and "reflection" was needed.
And Le Pen's firebrand father, Jean-Marie, warned the party had to "remain true" to its core principles.
Estimates showed Macron winning 65-66.1 percent of the vote compared with 35-33.9 percent for Le Pen.
Le Pen, speaking to supporters at a post-election FN gathering in Vincennes near Paris, said the outcome was "a historic, massive result" for the FN.
Le Pen said she had called Macron to wish him success.
"I called Mr Macron to congratulate him on his election, and because I have the country's higher interest at heart, I wished him success faced with the huge challenges France is facing," she said.
The 48-year-old nationalist said her score made the FN the country's "biggest opposition force" and announced she would lead the FN into general elections in June.
Le Pen said the contest against the pro-EU Macron had confirmed a new faultline "between patriots and globalists".
But the FN would have to "profoundly renew itself to be equal to this historic opportunity and the expectations expressed by the French in this second round," she warned.
"I suggest we begin a profound transformation of our movement to create a new political force," she said, adding: "I call on all patriots to join us."
Separately, Philippot said on TF1 television: "The National Front is going to evolve, it's going to use this rallying energy."
The party, he said, "is going to transform itself in a new political force which, by definition, will no longer have the same name."
Le Pen took the helm from her father in 2011 and has worked hard to try to cleanse it of an image for xenophobia and anti-Semitism.
But her swing to moderation has also alienated die-hard supporters, especially among loyalists of her father.
Sunday's result was the highest-ever score in a presidential election in the 44-year history of the FN, founded by Le Pen senior in October 1972.
But it still fell well short of the party's craving to capture the presidency, a post that in France carries vast powers.
Meanwhile, Le Pen's 27-year-old niece, Marion Marechal-Le Pen, said she felt a "certain amount of disappointment" at the result and said it was time for "reflection."
Jean-Marie Le Pen, asked about his daughter's plans for a makeover, said the party had to be "remain true... to the basics of the National Front."
"These are the basics of the National Front, which enabled this movement to be the only one which was set up in the 20th century and which has endured," the 88-year-old said on RTL radio.
Le Pen senior had harsh words for Philippot, saying he was "one of the main people to blame for Marine Le Pen's defeat."
"I was thinking perhaps that he had the idea of running away," Le Pen said sarcastically.