Pressure on French presidential candidate Francois Fillon to pull out of the election race intensified on Thursday as some lawmakers in his own camp urged him to abandon his scandal-tainted bid to save the conservatives from defeat.

The scandal, which erupted last week when a newspaper reported the 62-year-old ex-prime minister had paid his wife hundreds of thousands of euros for work she may not have done, has thrown Fillon's campaign off track.

Fillon denies wrongdoing, but opinion polls show support for Fillon eroding fast to the benefit of far right leader Marine Le Pen and a former investment banker, Emmanuel Macron, who is running as an independent.

"I think our candidate must stop," Alain Houpert, a conservative senator close to Fillon's former rival for the conservative ticket, Nicolas Sarkozy, told Public Senat television late on Wednesday.

In a new blow to Fillon's campaign, French investigators widened their probe to include two of his children, a source told.

And in what may prove a further damaging revelation, France 2 television said it would broadcast extracts of a 2007 interview of Fillon's Welsh-born wife Penelope telling British media that she had never worked as his assistant.

Her long-standing image as a woman-at-home is central to the allegations by the Canard Enchaine newspaper. Lawmakers who employ family members are doing nothing illegal in France, and the practice is commonplace, but the suggestion she did no real work has damaged Fillon's image, and could yet put him in court.

Fillon has said the work was genuine and will not stand down unless put under formal investigation. He held an emergency meeting with party grandees on Wednesday in which he urged them to stick by him for another two weeks - the time he estimated an official preliminary investigation would take to run its course.

But some in his camp appeared unwilling to allow him that much time, after one poll showed the hitherto favorite in the election would be eliminated in the first round.

Another survey published early on Thursday showed that 69 percent of people wanted Fillon to drop his bid.

"We need to change tactics, strategy," lawmaker Georges Fenech told RTL radio on Thursday, saying this needed to happen "without delay, today."