French conservative presidential candidate, François Fillon, said on Monday at a Paris press conference that he will not stand down despite an investigation by magistrates on suspicions of corruption.

After nearly two weeks of blistering attacks for allegedly using taxpayer money to pay his wife €830,000 for a fictitious parliamentary assistant’s job, the former Premier struck back, saying his wife was paid for real work. He did however admit that, although it is a common and legal practice for parliamentarians to hire family members, it was an error.

“What was acceptable yesterday…is no longer today.”

He defended the parliamentary employment of his daughter and son while they were students for which they received €84,000 in taxpayer money. Magistrates have also opened an investigation into them.

Fillon falsely asserted that the press took out of context a 2007 interview with The Sunday Telegraph in which his wife, the Welsh born Penelope Fillon, said she had never worked for her husband. Fillon accused the press of “going too far” in order to “lynch” him.

Fillon, who was favored to win the presidency, has fallen sharply in the polls since the satirical weekly Le Canard Enchainé first published the allegations on Jan. 25. He could be eliminated from the second round ballot. Many within his own Les Républicains party were calling for a new candidate.

Fillon stressed that French conservatives had elected him as their candidate in the primaries and “you cannot steal their choice,” Fillon said. “There is no plan B.” He insisted he is the only candidate who can prevent the far right from winning.

In a bid at transparency, Fillon followed the press conference by publishing on his web site all his wife’s pay slips from 1986 through 2013 as well as a declaration of the couple’s assets and wealth.

Penelope Fillon is also being looked into for €100,000 euros she received over a two-year period from a literary review owned by a billionaire friend of the family’s and for which she allegedly did little work.  In an interview Monday, a former director of La Revue des Deux Mondes, Michel Crépu, denied allegations he had “ostracized” Ms Fillon. “I never refused to publish a note from Penelope Fillon,” he said. “I’m curious to know where they were found?” He was alluding to some ten unpublished notes Penelope Fillon has now produced “by miracle.”

Too make matters worse for Les Républicains, investigators now suspect Laurent Fillon of influence peddling and abuse of office by issuing awards and honors in exchange for favors.

Early reactions indicate Francois Fillon managed to convince many of the doubters within his own camp but it remains unclear if he has convinced enough voters outside the circle to cast their ballots for him in April. If not, the run off in May could very well be between far right National Front candidate Marine Le Pen and the independent maverick, former banker and Economy Minister, Emmanuel Macron.