PARIS (AP) — Conservative candidate Francois Fillon refused to quit France's roller-coaster presidential race Wednesday despite receiving a summons to face charges of getting his wife and children taxpayer-funded jobs in which they allegedly did no work.

Calling the judicial investigation a "political assassination," Fillon urged his supporters to "resist" and said he would leave it up to French voters to decide his fate. Once a front-runner in the presidential election race, Fillon's chances have slipped since the probe began in January.

Cracks started to emerge in Fillon's Republicans party hours after his announcement, with the resignation of a top ally. But it's unclear whether Fillon's decision will dramatically alter the electoral landscape, since the polls are dominated now by far-right National Front leader Marine Le Pen and centrist independent candidate Emmanuel Macron.

The top two presidential vote-getters in France's April 23 ballot will head to a presidential runoff on May 7.

Fillon held an emergency party meeting Wednesday after receiving the legal summons and postponed a campaign stop, prompting media speculation that he could quit the race.

"I will not surrender," he told reporters at his headquarters later. "I will not withdraw."

Fillon denied all allegations and said legal procedures were not properly followed in the probe, which he called unprecedented and unacceptable during a presidential election campaign. He said he was summoned for questioning on March 15 "with the goal of being given preliminary charges."

Fillon's comments prompted a strong reaction from French President Francois Hollande, who said Fillon has no right to cast suspicion over the work done by police and judges or "create a climate of mistrust incompatible with the spirit of responsibility and, even worse, to throw extremely serious accusations against justice and, more broadly, our institutions."

The court summons was widely expected after the financial prosecutor's office pushed the case to a higher level Friday, opening a formal judicial inquiry.

The alleged fake jobs that Fillon gave his family are especially shocking to many voters because of Fillon's promise to cut government spending and his clean-cut image. The investigative weekly Le Canard Enchaine reported that payments were made to his wife, Penelope Fillon, and two of their five children that totaled more than 1 million euros ($1.1 million) over many years.

Fillon initially said he would withdraw from the race if he was charged, but later said he was determined to let voters judge him instead of investigators.

"France is greater than my errors," he said Wednesday.

After a preliminary investigation opened Jan. 25, the financial prosecutor's office decided Friday to launch a formal judicial inquiry. The list of potential charges now includes misappropriation of public funds, abuse of public funds and influence trafficking.

The investigation is going unusually quickly by French standards — one of the reasons that Fillon claims it is politically driven. The financial prosecutor's office was created in part to speed up the often-protracted French judicial process.

Le Pen is also facing legal investigations involving European Parliament assistants and party financing, which she calls baseless and politically motivated.

The Republicans party has no clear alternative candidate besides Fillon. The runner-up in the party's first-ever primary, Alain Juppe, has said he would not run in Fillon's place.

Bruno Le Maire, who also lost to Fillon in that primary, quit his position on Fillon's campaign team Wednesday, saying he could no longer back Fillon because the candidate had backpedaled on his promise to withdraw from the race if he was charged.

Fillon has not been charged yet, but the prosecutors apparently expect he will be.

"I believe in keeping your word. It is vital to the credibility of politics," Le Maire said.

But Bernard Debre of the Republicans rallied to Fillon's side, dismissing questions about whether the party should replace him.

"Well, 50 days ahead of (the election)? And by whom?" Debre asked.

Denise Mermut, an 18-year-old first-time voter walking near Fillon's Paris campaign headquarters, was unequivocal.

"Fillon should quit politics. It's shameful," she said, adding that she plans to vote for far-left candidate Jean-Luc Melenchon.

Zach El Maataoui, a young voter who plans to cast a blank ballot in the presidential election, said he was not surprised.

"The guy just wants power ... politicians are all scam artists," he said.