Francois Fillon's party has unanimously backed his candidacy for the French presidential election after Alain Juppe ruled himself out.
An emergency meeting of Les Republicains had been called because of the waning support for Mr Fillon.
Senate speaker Gerard Larcher said: "The political committee, after a wide-ranging exchange, unanimously renewed its support for Francois Fillon."
:: How exactly do the French elections work?
Les Republicains' leader, Bernard Accoyer, confirmed the party was backing Mr Fillon and said it had reunited and was re-launching his campaign.
:: Elections: France faces remarkable moment as Le Pen and Macron may be in run-off
Mr Fillon was the frontrunner until mid-January when the Canard Enchaine newspaper claimed he had paid his wife, Wales-born Penelope Fillon, and two of their children, nearly €900,000 (£780,000) as parliamentary assistants or advisers, even though no work was allegedly done.
His support has dwindled after he disclosed he would face corruption charges over the scandal.
He is now behind far-right candidate Marine Le Pen and centrist Emmanuel Macron in the opinion polls.
:: What you need to know about the French elections - and why
It was believed that Mr Juppe had indicated he was willing to replace Mr Fillon if the party wanted him to.
A poll on Sunday suggested he would have a better chance at reaching the run-off than Mr Fillon.
But on Monday afternoon, Mr Juppe said: "I confirm for a final time that I will not be a candidate to be president of the republic."
:: French presidential elections: Who is Francois Fillon?
Mr Fillon has vowed that "no one" can force him to quit his bid for the presidency - despite calls within his own Republican party for him to step down.
During a rain-soaked speech to thousands of supporters in Paris on Sunday, the conservative candidate refused to say whether he intended to fight on.
Mr Fillon is yet to react to the party's backing.
According to AFP, Mr Fillon told the meeting: "We have lost too much time with vain debates, leaving the way open for the far right and candidates on the left who are rubbing their hands over our disunity.
"Our voters will not forgive those who maintain the poison of division."