Francois Fillon was fighting to keep his embattled French presidential bid alive on Monday as former president Nicolas Sarkozy piled pressure on him ahead of a crisis meeting of their rightwing Republicans party.
The conservative Fillon, 63, was once a clear favourite to win France's two-stage election in April and May but his campaign is mired in accusations he used public funds to pay his wife for a fake parliamentary job.
Waiting in the wings is another former prime minister, Alain Juppe, whom Fillon beat in a primary vote to chose the candidate for the conservative Les Republicans party in November.
Sarkozy, who picked Fillon as his prime minister from 2007-2012, called on him and Juppe to meet "to find a dignified and credible way out of this situation which cannot continue and which is creating serious problems for the French people."
Juppe, 71, is seen as the most obvious replacement for Fillon but he has consistently ruled himself out of contention. He is expected to brief reporters early on Monday.
Despite a raft of desertions from his own camp, Fillon came out fighting again during a prime-time TV interview on Sunday, seemingly buoyed by a large rally by his supporters in Paris on Sunday.
"No one today can prevent me being a candidate," he told France 2, adding that the accusations against him were "aimed at stopping me being a candidate."
The chaos in Fillon's camp has made an already unpredictable election even harder to call.
Surveys suggest that if the election were held today, centrist pro-business candidate Emmanuel Macron and the far-right leader Marine Le Pen would be the top two candidates in the first round on April 23 and that Fillon would be eliminated.
Polls suggest that Macron would beat Le Pen in the decisive second round, but after the shock of Donald Trump's rise in the United States and Britain's vote to leave the European Union, analysts caution against bold predictions.
- Hollande's 'final duty' -
Fillon, fired up by the rally in the shadow of the Eiffel Tower attended by tens of thousands of flag-waving supporters, hit back at suggestions Juppe could replace him on Sunday.
"If the voters of the right and the centre wanted Alain Juppe, they would have voted for Alain Juppe," he said.
But even his TV interview was not without controversy as he came under fire on social media for repeatedly stressing he was "not autistic" and could recognise the problems his campaign was suffering.
The current French leader, Francois Hollande, warned in an interview with six European papers published on Monday that the threat of a Le Pen presidency was real but that he would fight to prevent it happening.
"The far-right has not been so high (in the polls) for more than 30 years but France will not give in," the president said.
France "is aware that the vote on April 23 and May 7 will determine not only the fate of our country but also the future of the European project itself," he added.
Le Pen, 48, has vowed to ditch the euro as France's currency if elected and hold a referendum on the country's membership of the European Union.
Hollande, who has battled stubbornly high unemployment throughout his five-year term and has suffered low poll ratings, decided last year not to run for a second term.
- 'Clean candidate' -
He said it was his "last duty... to do everything to ensure that France is not convinced by such a plan" of taking the country out of the EU.
Fillon, a devout Catholic, beat Juppe in the Republicans' primary in November, pulling off a surprise victory by campaigning as a "clean" candidate.
He was the frontrunner in the presidential race until Le Canard Enchaine newspaper alleged in late January that he paid his wife Penelope and two of their children nearly 900,000 euros ($950,000) as his parliamentary assistants.
Fillon had previously promised to quit if he were charged but has since pulled back from the pledge.
He portrays himself as a victim of a politically motivated investigation and biased media who intends to put his case directly to the people.
Fillon's British-born wife Penelope, who accompanied him at the rally, broke her silence earlier Sunday, telling Le Journal du Dimanche newspaper she had carried out "a lot of different tasks" for her husband during his lengthy career.
She had also urged him to "keep going to the end" but said only he could make the final decision.