PARIS (Reuters) - Heavyweight centrist Francois Bayrou joined calls on Sunday for French presidential candidate Francois Fillon to withdraw from the race, as his own conservative camp mounted pressure on the back of a deepening financial scandal around his family.

Francois Fillon, former French prime minister, member of The Republicans political party and 2017 presidential candidate of the French centre-right, visits the Salon des Entrepreneurs (Entrepreneurship fair) in Paris, France, February 1, 2017. REUTERS/Benoit Tessier

Fillon, 62, has seen his approval ratings slide since satirical newspaper Le Canard Enchaine reported on Jan. 25 he had paid his wife hundreds of thousands of euros of parliamentary money for work she may not have done.

Bayrou has yet to endorse a candidate. A respected figure, he has run unsuccessfully for president three times in the past and carries a core vote of about 6 percent. He said he would not align with the center-right if Fillon remained candidate.

“He has no other alternative,” Bayrou told media outlets Le Grand Jury RTL-Le Figaro-LCI on Sunday when asked if Fillon should drop his bid.

Two weeks ago Fillon was the election frontrunner and seemed poised for an easy ride into the Elysee palace in the spring elections. But now he cannot be sure of reaching the second round.

The latest major survey of voting intentions showed the former conservative prime minister trailing in third place behind far-right leader Marine Le Pen and independent Emmanuel Macron. Both Le Pen and Macron campaigned in the city of Lyon at the weekend.

Fillon, the mainstream center-right Republicans party nominee, maintains his wife Penelope carried out real work as his parliamentary assistant. He has said he will only drop his presidential bid if he is placed under formal investigation.

But a growing number of party grandees and allies outside say the damage has been done to his reputation already.

“One cannot come up with a program that requires sacrifices from everyone, especially from those who are at the bottom of the pyramid, while reserving privileges for those who ... have power,” Bayrou said.

Bayrou said that he would back Alain Juppe, another former prime minister who Fillon beat for the conservatives ticket, if Fillon pulled out and Juppe was named to replace him.

Senator Bruno Gilles, head of The Republicans in the Bouches-du-Rhone region, said in a radio interview on Saturday that the party faithful had “turned the page” and overwhelmingly wanted a change of candidate.

“This scandal is doing us more damage every day, and we can’t wait another two weeks,” Gilles told France Bleu Provence radio. “There are presidential and legislative elections at stake and, beyond that, the survival of our political party.”

The senator added: “This could go as far as a party split.”

A new opinion poll for the Journal du Dimanche showed the proportion of French voters who believe Fillon to be “honest” has plummeted to 23 percent from 50 percent last November. Pollster Ifop surveyed 1,007 people from Feb. 3-4.