PARIS (AP) — The French financial prosecutor's office decided Friday to open a judicial inquiry surrounding the allegedly fake parliamentary aide jobs that conservative presidential candidate Francois Fillon gave to his wife and two of his children.

After a preliminary investigation opened Jan. 25, the prosecutor's office decided to move forward with the case. However, no one was named in the judicial investigation on a list of charges, including misappropriation of public funds, abuse of public funds and influence trafficking.

It was a sign that the prosecutor's office intends to question others in the case, enlarging the circle of those who risk being charged, an official in the prosecutor's office said.

The decision to take the Fillon case to a new level comes as the French presidential campaign moves into full steam.

Fillon, a conservative and former prime minister, had been the front-runner for the French presidency, but his candidacy has stumbled after the allegations. Fillon admits that he hired his wife and children as parliamentary aides, a practice that is legal in France.

However, there are suspicions that neither his wife Penelope nor a son and daughter actually worked for the pay — which totaled as much as 1 million euros ($1.1 million) over many years.

Fillon has denied any wrongdoing and vowed to carry on his campaign amid the probe. However, he has said he would end his presidential bid if changed.

The announcement came in the midst of a Fillon campaign rally Friday in Maisons-Alfort, outside Paris.

"If I am attacked, so relentlessly attacked, it is because I clash with the spineless consensus that only likes the right when it walks in the shadows," Fillon told the crowd, suggesting that his legal troubles were part of a bid to bring him down.

The move by the financial prosecutor's office means the case will now be turned over to investigative judges who can file formal charges or throw the case out. The statement by prosecutors attributed the decision to open a judicial investigation in part to the long time period covered in the case.

Since the scandal erupted, centrist presidential candidate Emmanuel Macron and far-right National Front leader Marine Le Pen have moved ahead of Fillon in the polls for France's two-round, April 23-May 7 presidential election.

Le Pen, however, is dealing with her own corruption scandal linked to aides in the European Parliament.

One close aide was placed under investigation this week. Le Pen refused to appear before an investigating judge for questioning on Wednesday. Her bodyguard, who once served as her aide for several months, was questioned and released.