Former Tory Party chairman Grant Shapps has said there is growing support among MPs for a leadership contest following Theresa May's chaotic conference speech.
Mr Shapps, who has been revealed as one of the ringleaders of the plot to oust the Prime Minister, said there is a "broad spread" of opinion among Conservative MPs who believe they cannot carry on as they were.
"They are Remainers, they are Brexiteers," he told BBC Radio 4's Today programme.
"A growing number of number of my colleagues, we realise that the solution isn't to bury our heads in the sand and just hope things will get better.
"It never worked out for Brown or Major and I don't think it is going to work out here either."
However, Mrs May's allies have publicly rallied round their embattled leader.
Home Secretary Amber Rudd insisted the Prime Minister "should stay" despite the "presentation fails" in her calamitous conference speech and Margot James attacked sacked ministers for wanting to "get their own back".
Ms Rudd called on the party to look at the policies set out at the Tory conference instead of the "presentation fails".
In an article for The Daily Telegraph, she said: "We, Theresa May's Government, want to ... set out a better path, one that actually leads to a prosperous, secure and united country.
"We can do that, and we will under her leadership. She should stay. Do not doubt that the Prime Minister's absolute commitment to tackling the injustices is a real one. And as the Prime Minister also said this week, we are at a turning point for the nation.
"Trust that it is us who will take Britain in the right direction."
Communities Secretary Sajid Javid said the comments were "spot on".
Business minister Ms James hit out in The Times at "ex-ministers who are extremely embittered individuals who just want to get their own back on the fact they don't feel recognised".
Critics of the PM were said to be attempting to "drum up" a delegation of around 30 MPs to tell her she has lost support and must resign.
Challenged by The Times on whether he was behind a push to pressurise the PM into quitting, Mr Shapps said: "I think having lost an election the party must look for a new leader to take us forward."