The Prime Minister was challenged repeatedly by fellow Tories who reminded Mrs May that she had previously said the Labour leader was “not fit to govern”.
It came as Brexiteer Tories circulated a draft parliamentary motion calling for the Prime Minister and members of her cabinet to be censured and have their pay docked for not delivering Brexit on time.
At Prime Minister’s Questions, the cross-party talks set to begin on Wednesday afternoon were also criticised by the SNP, who said Mr Corbyn was about to step into a “trap”.
"Let me ask her, had she been the leader of the opposition, and invited into a trap like this, would she have been foolish enough to accept?"
Mrs May said: "I think members of the public expect us to reach out and find a way through this. They want a solution.”
But she faced an onslaught from her own side that casts doubt over the Prime Minister’s ability to hold the Conservative Party together if she reaches a soft Brexit compromise with Mr Corbyn.
Former Brexit minister David Jones asked: "Does it remain the position of the Prime Minister that the leader of the opposition is not fit to govern?"
Mrs May replied that "I do not think the Labour Party should be in Government”, adding that after the Salisbury poison attack, Mr Corbyn "said he preferred to believe Vladimir Putin than our own security agencies".
Another Tory MP, Lee Rowley reminded the Prime Minister that last week she said "the biggest threat to our standing in the world, to our defence, and to our economy" was Mr Corbyn.
"In her judgment what now qualifies him for involvement in Brexit?" Mr Rowley asked.
Tory MP Caroline Johnson said that “if it comes to the point when we have to balance the risk of a no-deal Brexit versus the risk of letting down the country and ushering in a Marxist, anti-Semite led government, what does [the Prime Minister] think, at that point, is the lowest risk?"
SNP Westminster leader Ian Blackford complained that his party had been left out of the process, despite having consistently "sought compromise".
Mrs May replied she was meeting Nicola Sturgeon and the First Minister of Wales later today.