PARIS -- After more than a week of wrangling over the outcome of its hotly contested party election, the leadership of France's center-right opposition party on Monday confirmed Jean-François Copé, a right-leaning protégé of former president Nicolas Sarkozy, as the party's new chief, staring down a last-minute legal challenge from his centrist rival, François Fillon.
In a statement, an internal commission of the party, the Union for a Popular Movement, declared Mr. Copé the winner by 952 votes, a far wider margin of victory than the 98 votes that it announced on Nov. 19. The commission, charged with both a recount and an investigation into allegations of vote-rigging, said it had decided to exclude several thousand ballots cast in precincts in and around Nice, on the French Riviera, as well as in Paris and the Pacific territory of New Caledonia, citing evidence that voting there had been tainted.
The disputed election has sown confusion and embarrassment across France and in particular within the already bruised party, known as the U.M.P. for its initials in French. The drawn-out battle, which has played out on live television and via social media networks, follows Mr. Sarkozy's loss in the presidential race in May, and then the party's defeat in legislative elections in June. Now, much like the Republican Party in the United States, the U.M.P. faces tough choices as it tries to redefine itself and work through a crisis of identity.
Mr. Copé was swift to seize the moment to call once more for party unity.
"I invite everyone to chose forgiveness rather than division, teamwork over personal ambition," he said in a statement. "There is no winner or loser -- just one family, the U.M.P. The time for internal squabbles is behind us."
But Mr. Fillon refused to concede, calling the latest announcement a "power play" by a commission he has said is stacked with Copé loyalists. Mr. Fillon vowed to pursue his challenge of the result in civil court, asserting that he was in fact the winner, by 26 votes.
The tight leadership race between Mr. Copé, 48, and Mr. Fillon, 58, is as much a battle for the direction of the U.M.P. as for power. Mr. Copé wants to move the party further right to challenge the popularity of the far-right National Front and its leader, Marine Le Pen, while Mr. Fillon favors Gaullist, more centrist positions.
The ferocity of the U.M.P.'s civil war has stunned political commentators. Most agreed that the fight would leave lasting scars on the party, which for the last decade has united a vast swath of the political landscape, from the center to the anti-immigrant right. Few, however, were yet prepared to predict the party's demise.
"It is like a death in slow-motion," said Pascal Perrineau, director of the Center for Political Research at the Institut d'Études Politiques in Paris, also known as Sciences Po. "We have to wait a few days to see whether the suicide attempt is successful, or whether the corpse is still moving."
Mr. Perrineau predicted that even if the U.M.P. survived, the episode might signal the end of a unified French right. That would create major hurdles against the Socialist government of President François Hollande -- not to mention blunting efforts to build momentum before municipal and European parliamentary elections in 2014.
"The right is now several 'rights' that will be obliged in the coming years to find some way of approaching each other," Mr. Perrineau said.
Alain Juppé, a widely respected former prime minister who failed to broker a compromise over the weekend, predicted that Monday's declaration would not be end the matter. "I don't think anything is settled," he told reporters after the announcement.
Mr. Juppé had earlier urged Mr. Sarkozy, who has all but withdrawn from French public life since May, to intervene. "He is the only one today who has enough authority to possibly suggest a way out," Mr. Juppé told French radio.
The former president, 57, reached out on Monday to both rivals, making a lengthy phone call to Mr. Copé and later hosting Mr. Fillon for lunch at his Paris offices. Mr. Sarkozy has no formal role within the U.M.P. but is widely believed to be weighing a 2017 presidential run, and has sought to remain neutral.
Claude Guéant, a close ally of Mr. Sarkozy and his former interior minister, did not exclude Mr. Sarkozky's weighing in publicly at some point.
"We cannot continue this dizzying plunge into the abyss," Mr. Guéant said in a radio interview. "I doubt that he wants to enter the fray. But it's clear that something needs to happen."
Meanwhile, others are simply calling for the election to be held again.
Nathalie Kosciusko-Morizet, a former environment minister who failed to garner enough endorsements to seek the U.M.P. leadership herself, announced on Monday that she had set up an online petition calling for a new election in order to restore the party's "political legitimacy." By late afternoon, the petition had garnered more than 16,500 signatures.
This article originally appeared in The New York Times.