PARIS (Reuters) - French presidential candidate Francois Fillon struck back on Thursday over the scandal sapping his campaign, calling for fraud investigators to drop their inquiry into the “fake jobs” affair.

Marine Le Pen, French National Front (FN) political party leader and candidate for the French 2017 presidential election, attends the 2-day FN political rally to launch the presidential campaign in Lyon, France February 5, 2017. REUTERS/Robert Pratta

Lawyers for Fillon, once a frontrunner to win election in May but now a third-placed loser according to opinion polls, publicly denounced the financial prosecutor’s inquiry into misuse of public funds as illegal and questioned the impartiality of its investigators.

The scandal involves mainly his wife, Penelope, who a satirical weekly said received almost a million euros ($1.07 million) for work as a parliamentary assistant and literary reviewer - work, it said, she did not properly carry out.

The conservative former prime minister denies this and says his wife carried out work that was indispensable to his career as a politician, though he has apologized for employing a family member, something which is legal in France.

But the charge continues to dog his campaign and opinion polls in the past 24 hours have shown his poor ratings persisting, despite a combative news conference on Monday when he relaunched his campaign.

Both Fillon and his British-born wife have been questioned by fraud police as part of the inquiry. Two of the couple’s children, Marie and Charles, who are in their 30s and also did some work for their father, were due to be questioned on Thursday.

Lawyers for Fillon and his wife said on Thursday they had asked the financial prosecutor - a new institution introduced by the Socialist government only in 2013 - to wind up the inquiry.

“The financial prosecutor has no jurisdiction and its inquiry is therefore illegal,” Antonin Levy, one of the lawyers, told a news conference.

“This investigation violates the most basic principles of the French constitution.”

They said they had lodged a complaint for breach of confidence relating to information appearing in the press which cast doubt on the “impartiality” of those holding the inquiry.

LE PEN OR MACRON?

Though the presidency seems to be slipping from his grasp, Fillon, a 62-year-old former prime minister, has managed to stem a rebellion in his Republicans party.

But the scale of the task now facing Fillon and the center right has been reinforced by polls which show him certain to crash out of the election in the first round on April 23.

These polls see the far-right Marine Le Pen meeting centrist independent Emmanuel Macron in the May 7 runoff - with Macron, a former investment banker who has never held elected office, easily beating the National Front leader.

Fillon, who says he wants to change France’s “software” and is pushing free-market policies which include big cuts in public spending and civil service numbers, took his program to the town of Poitiers on Thursday.

He was to see local Republicans close to Alain Juppe, another former prime minister and rival for the candidacy, in further efforts to rally center-right forces behind him.

Le Monde newspaper quoted Fillon as saying that he saw the next two weeks as crucial for his campaign and it was wrong to think Macron would easily beat Le Pen in a runoff.

“My voters will go straight to Le Pen,” he told a group of journalists, according to le Monde.

“People of the right who saw themselves deprived of their candidate (Fillon) would be extremely angry.”

The unpredictability of the French election campaign has rattled regional bond markets, pushing up the premium that investors demand for holding French over German government debt to multi-year highs earlier this week.