The race to lead France's conservative opposition descended into chaos, with both contenders alleging fraud in a vote that highlighted a deep split between rightists and centrists since the party lost power in May.
The bickering wrecked a contest designed to give the right a fresh start after it lost its 17-year hold on the presidency in May, and prompted political commentators to warn that the Union for a Popular Movement (UMP) could collapse.
Jean-Francois Cop, a hardline disciple of Nicolas Sarkozy, declared in the early hours of Monday that he was 1,000 votes ahead of Francois Fillon, but the former president's long-serving prime minister said he had a lead of 224 votes.
The influential daily Le Monde daily, running a front-page photo of a bare podium at UMP headquarters, said it was hard to imagine a worse outcome for the party.
"It's a catastrophe. The Socialists must be pleased with this," lamented a member of Fillon's team privately.
"Nicolas Sarkozy must be happy too. He must be saying to himself that things are not going well without him."
By early evening, the party was still counting votes and could not say whether a result would come before Wednesday.
The infighting in the main opposition party also takes some of the pressure off Socialist President Francois Hollande, whose approval ratings have slumped to as low as 36 per cent as he struggles with rampant unemployment and stalled growth.
The contest would normally decide the UMP's candidate for the 2017 presidential election, but surveys indicate that two-thirds of party members think Sarkozy has a better chance of wresting power back from the ruling Socialists.
The election row has further fuelled speculation of a comeback by Sarkozy, who has told aides he will feel obliged to return if the Socialists fail to revive the sickly economy.
"Even without knowing who the winner is, we can state that the true victor of this vote is called Nicolas Sarkozy," the
business daily Les Echos wrote in an editorial.
Alain Juppe, a former foreign minister and a key figure in founding the UMP, condemned what he called "a contest of egos" that he said threatened the party's very existence.
While Fillon, a mild-mannered 58-year-old, urged UMP supporters to be patient and await the final vote count, Cop told BFM television that centres where ballots had been rigged should be removed from the count.
"This is known as ballot-stuffing. It's pretty pathetic," he said. "If we discount the results from centres where there was fraud, I win, and if we include them I am not sure that I would lose either."
Fillon said that nobody should claim victory before the results were official.
The UMP, founded by former conservative president Jacques Chirac in 2002 to merge various centre-right parties including his own Rally for the Republic (RPR), is reeling from the loss of the presidency, parliament and most French regions.
The vote to pick a successor to Sarkozy was meant to determine whether the UMP would cleave to the centre ground under Fillon, in keeping with the party's decades-old roots, or move right under the combative Cop in a quest to regain power.
Instead, the disarray looked more likely to bolster far-right and centrist parties, analysts said.
Cop, 48, said more ballots had been counted than there were voter signatures at centres where Fillon was in the lead, while Fillon's spokesman alleged "massive fraud" at voting stations in areas loyal to Cop.
The Conservative daily Le Figaro talked on its front page of an open crisis at the UMP, and the political weekly L'Express said even Sarkozy could struggle to unite and lead a party torn by divisions and infighting.
"The entire kingdom of the right is in ruins," Christophe Barbier, L'Express editor, told Reuters news agency.
"Whoever the winner is today, his legitimacy will be weak. Sarkozy can only make a comeback if the party is in good health."
Fillon, an urbane former lawyer, has targeted those centre-ground voters who abandoned Sarkozy to support Hollande in the May election, put off by Sarkozy's aggressive manner and hard-line stance on issues such as immigration.
Cop, a more polarising figure, has stirred up criticism by complaining that "anti-white" racism is rife in city suburbs, a
stand that appeals to the one in five people who voted far-right in the first round of May's election.
Cop, who played a central role in Sarkozy's ban on full-face Islamic veils, has said he will follow in Sarkozy's
path but would stand aside in 2017 if Sarkozy wanted to run.