France's conservative Republican party has brought forward talks to discuss its backing for its presidential candidate, Francois Fillon.
The committee will meet on Monday amid calls for Mr Fillon to step down over an inquiry into political payments made to his wife.
The former prime minister denies wrongdoing and plans a major rally near the Eiffel Tower in Paris on Sunday.
Mr Fillon has seen his popularity slip in opinion polls.
Speaking to supporters in Paris on Saturday as he marked his 63rd birthday, he said that those attacking him over his presidential bid were "trying to kill a desire for change".
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The latest opinion polls suggest that he would be eliminated in the first round of presidential election voting on 23 April, with far-right leader Marine Le Pen and liberal Emmanuel Macron likely to progress to contest the election run-off on 7 May.
A survey published on Saturday in the French newspaper Journal du Dimanche (in French) suggests that 71% of those polled want Mr Fillon to step down.
In another blow to Mr Fillon's campaign, his spokesman announced on Friday that he was quitting.
Thierry Solere's resignation is one of a slew of notable departures, including the campaign treasurer on Thursday.
Mr Fillon's woes have raised speculation that Alain Juppe, also a former prime minister, could return to the race if he were to pull out.
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Mr Juppe was overwhelmingly defeated by Mr Fillon in the Republicans' primary in November, securing only 33% of the vote to Mr Fillon's 66%.
Sources close to Mr Juppe said he would be prepared to step in, but only with the unanimous support of the party and only if Mr Fillon were to go voluntarily.
Mr Fillon has so far said he has no intention of stepping down despite the continuing haemorrhage of allies.
For weeks he has fought allegations that his wife was paid for a number of years for work she did not do as his parliamentary assistant.
More than 60 politicians have said they can no longer support him.