Story highlights François Fillon said he would be told on March 15 that he is under formal investigation

France votes on April 23, with a runoff May 7 if no candidate wins first round outright

Paris (CNN) Embattled French presidential candidate François Fillon said Wednesday he will persevere in the race despite an ongoing inquiry into allegations that he paid his wife and children for work they did not do.

In a televised statement in Paris, Fillon announced that he will be placed under formal investigation on March 15, yet he would not step aside.

"I will not resign. I will not give in. I will not withdraw," he said. "I will go to the end because it is democracy that is being defied. I ask you to follow me."

Fillon said the timing of the meeting with magistrates was intended to damage the Republican Party's chances in the election, and that he was the victim of a "political assassination."

The announcement prompted one member of his campaign to quit, saying Fillon had gone back on his word.

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