By Sophie Louet
PARIS (Reuters) - More cracks emerged in French conservative Francois Fillon's campaign for the presidency on Thursday, a day after news that he faces a formal investigation for allegations he misused public funds.
A flash opinion poll by Harris Interactive showed that only 25 percent of people now want him to continue as a candidate, down from 35 percent a month ago, while within his party The Republicans there were more resignations after his decision on Wednesday to stay in the race.
While Fillon campaigned in southern France on Thursday ahead of a rally in the city of Nimes, poll favorite Emmanuel Macron announced his full centrist manifesto and far-right National Front leader Marine Le Pen was due to give a presentation on the role of the French state in the economy.
With less than two months to go to the April 23 first round vote, polls point to a second-round showdown on May 7 between Macron and Le Pen that Macron would win.
One of the first opinion polls partly taken after Fillon's legal woes deepened on Wednesday showed his support dipping below 20 percent for the first time in a week.
The Elabe poll, carried out between Tuesday and Thursday, showed 19 percent of people planning to support Fillon in the first round, down from 20-21 percent in the last Elabe poll carried out from Feb. 18-20.
He trailed Le Pen, on 27 percent and Macron, on 24 percent.
Fillon already suffered a blow on Wednesday when adviser Bruno Le Maire quit his campaign in protest against his decision to fight on.
DEFECTIONS FROM FILLON CAMP
On Thursday, deputy campaign director Sebastien Lecornu and adviser Vincent Le Roux followed Le Maire's lead, along with a number of more junior campaign staff.
Fillon denies any wrongdoing and stepped up his attacks on a French judiciary he insists is biased against him.
"I have been singled out by the judicial system. It's as if I had to be brought down at all costs," he said in an interview with the regional newspaper Midi Libre.
Fillon is to be questioned by investigating magistrates on March 15 with a view to being put under formal investigation. Supporters plan to organize a rally in Paris on Sunday in support of his campaign.
Sources in the Fillon camp have said there was a strong push by some in the party on Wednesday to have former prime minister Alain Juppe stand in Fillon's place, but the plan was vetoed by Nicolas Sarkozy, the former president.
Georges Fenech, a lawmaker who led a failed rebellion against Fillon last month, confirmed on Thursday that he was among those wanting Juppe to stand in Fillon's place.
"Unhappily, I am convinced that Francois Fillon is about to fall," he told France Info radio. "It seems to me that today only he (Juppe), with all his experience, can carry the flame."
Juppe, 71, insists he has no interest in replacing Fillon.
(Reporting by Sophie Louet; Writing by Andrew Callus; editing by Mark John)