"I think our candidate must stop," Alain Houpert, a senator close to Fillon's former rival for the conservative ticket, Nicolas Sarkozy, told Public Senat television.
France 2 television yesterday broadcast extracts of a 2007 interview of Fillon's Welsh-born wife Penelope telling Britain's Daily Telegraph that if she had not had her last child she would have looked for work.
She added that beyond helping her husband during campaigns, she had done nothing more.
"I have never been actually his assistant or anything like that. I don't deal with his communication,"she said.
Her lawyer, Pierre Cornut-Gentille, said in a statement that the interview had been taken out of context and that she had always done her utmost to remain discreet and not appear to have a public role.
Financial investigators are widening their probe to include two of the Fillons' children, who were also hired to help him out, a source told Reuters.
Fillon himself pressed on with campaigning in the Ardennes region in northern France, telling a rally of about 1000 people to "help him resist" against orchestrated efforts by his political opponents to break him and the party.
He once again defended his actions as "nothing illegal" and sought to grab back the political high ground by attacking the other presidential candidates.
"I feel like someone who is being attacked unjustly on all sides. But I am ready to defend myself," he said when a few cries of "Resign!" rang out from a crowd.
French lawmakers are allowed to employ family members, but the suggestion that Penelope Fillon 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 Thursday in which he urged them to stick by him for another two weeks - the time he estimated a preliminary investigation would take to run its course.
But some appeared unwilling to give him that much time after one poll showed the hitherto favourite would be eliminated in the first round of the election on April 23.
Another survey showed 69 per cent of people wanted Fillon to drop his bid.
"We need to change tactics, strategy," lawmaker Georges Fenech told RTL radio. "We're like the orchestra on the Titanic as it sinks," he said in an earlier comment.
Another legislator, Philippe Gosselin, called on former Prime Minister Alain Juppe, whom Fillon beat in a runoff for the party nomination, to think of stepping in as an alternative.
But in the right-leaning newspaper Le Figaro, party stalwarts such as former candidates Bruno Le Maire and Nathalie Kosciusko-Morizet offered Fillon their "total support".
Aside from Juppe, other names being mentioned are Francois Baroin, a former Finance Minister, Valerie Pecresse, who heads the prosperous Ile de France region around Paris, and Xavier Bertrand, who won a notable victory against Le Pen in regional elections in 2015.
The scandal has heightened investor concerns that National Front leader Le Pen could win and take France out of the euro and the European Union.
Opinion polls routinely show Le Pen making it through to a second round, but being soundly defeated in the runoff vote by any candidate - be it Fillon or the centrist Macron.
