PARIS (AFP) – Francois Fillon, the rightwing Republicans party candidate for the French presidential election, is ensnared in a corruption scandal that has been dubbed “Penelopegate”.

Here is the furore explained in six key questions:

– Who is Francois Fillon? –

He was prime minister from 2007-2012 under rightwing president Nicolas Sarkozy, the high-point of a nearly 40-year career in politics.

He emerged as the surprise presidential nominee for the Republicans party in November, promising to slash public spending, cut bureaucracy and adopt family-friendly policies.

Since his victory in the primary, polls had consistently shown him as the most likely winner of the two-round election in April and May.

– What is he accused of doing? –

On January 25, the Canard Enchaine weekly, which mixes satire and investigative reporting, broke the news that Fillon had employed his Welsh-born wife Penelope as a parliamentary aide.

Citing pay slips, it said she was employed from 1998 to 2007 either directly by Fillon, or by the man who stood in for him in parliament during Fillon’s time in government.

Penelope was also paid around 5,000 euros ($5,370) a month between May 2012 and December 2013 by the magazine Revue des Deux Mondes, owned by a friend of Fillon, the newspaper said.

The Canard initially estimated Penelope’s pre-tax income at around 500,000 euros, but in this week’s edition said the family’s overall pre-tax income from the contracts was around 1.0 million euros.

Fillon also paid his two children Marie and Charles 84,000 euros as parliamentary assistants from 2005-2007, the paper said.

– Is this illegal? –

Employing a family member as a parliamentary aide is a widespread practice in France and not illegal, unlike in Germany or at the European parliament.

Fillon admits to paying his wife and children.

But there are suspicions that Penelope did no work for her parliamentary salary, which reached over 10,000 euros pre-tax a month in 2007, and that she contributed very little to the literary review.

An investigation was launched last week into the possible misuse of public money, a criminal offence.

Penelope had neither a parliamentary security pass nor a work email account.

Moreover, she has been a low-key political wife known to prefer life at the couple’s country chateau with their five children and horses than among the Parisian chattering classes.

“Up until now, I was never involved in my husband’s political life,” she said last year.

What she meant to say, Fillon claimed last week, was that she never played a frontline role.

– Is that all? –

No. Investigative website Mediapart and newspaper Journal du Dimanche reported that the 62-year-old candidate pocketed 25,000 euros in funds earmarked for parliamentary aides between 2005 and 2007.

During that time he was a member of the upper house, or Senate.

There is also renewed public interest in a consulting firm he set up in 2012 at the end of his five-year term as prime minister.

The Canard Enchaine reported that the consultancy had paid Fillon an after-tax salary of 757,000 euros since 2012. Opponents are demanding he reveal the source of the money.

– What does Fillon say? –

In media interviews and in a defiant speech at the weekend flanked by his stony-faced wife, he accused his opponents of using Penelope to attack him.

He has called the revelations a “plot,” “mudslinging” and an “institutional coup” but has yet to present evidence publicly of his wife’s work.

He is cooperating with fraud investigators who interviewed him and Penelope for five hours on Monday. On Tuesday, the investigators seized documents from Fillon’s parliamentary office.

– How might this affect the election? –

Fillon’s approval ratings have fallen sharply and a new survey published on Wednesday suggested for the first time he would crash out in April’s first round.

In this scenario, the main beneficiary would be 39-year-old centrist Emmanuel Macron who would overtake Fillon to go through to the run-off against far-right leader Marine Le Pen.

Le Pen might benefit too, but her party is embroiled in its own expenses scandal at the European parliament.

Much will depend on the investigation into Fillon, which he said Wednesday would be completed in the next two weeks.

If he were to withdraw — a prospect being discussed among senior Republicans — the party would have to nominate a new candidate.

This process is still unknown and could lead to either a new primary, a vote by party members, or a nomination by the senior leadership.