MP Grant Shapps previously declared he had the support of 30 Conservative MPs to launch a vote of no confidence against Mrs May following her disastrous party conference speech in Manchester, but has since dropped his rebellion.
Speaking to Sky News, Mr Shapps said: “Six months ago, a year ago, people were saying after that failed election she’s only got until next March when we actually leave.
“I don’t think many people now are saying she’s going to leave in March, because she’s then got the negotiation period until the end of 2020, possibly 2021, we learned this week.
“When Theresa May takes a decision people actually go, ‘ah, OK, well, I may not agree with all of that but, you know what, the decision’s been made, I’m prepared to follow’.”
Pointing to the Prime Minister’s long future, he added: “I think it’s perfectly conceivable now that she leads us into the next election and I think potentially even wins that election.”
However he warned Mrs May needed to offer greater clarity surrounding the Brexit process and provide firm decisions.
He said: “So I think it is possible, but we do need to have more decisions made, less waiting around for things, get things out in front of Parliament, not impossible, maybe 30 per cent or 40 per cent.
“I think the problem comes when things are allowed to float, drift and decisions aren’t made and that’s when you tend to get these kind of heated-up moments.”
Support for Mrs May also seems to be on the rise after Amber Rudd and Iain Duncan Smith called for greater unity in the Conservative Party and for rebel Tory MPs to back the Prime Minister in key upcoming Brexit votes.
Writing in The Sunday Telegraph the former ministers said: “Jeremy Corbyn will do everything he can to stop us.
“That includes cynically trying to frustrate the Brexit process for his own political ends, as he will try to do next week when the Commons votes again on the EU Withdrawal Bill.
“So it behoves us all to demonstrate discipline and unity of purpose in support of the Prime Minister.
“We cannot allow ourselves to become divided and risk losing the precious chance to go on implementing policies that transform lives.”
However former Prime Minister Gordon Brown said Mrs May’s position may become untenable if the Government loses a vital vote this week on its Brexit legislation.
He noted the fixed-term Parliament arrangement could “make it possible” for the Conservative Party to remain in Government, but warned Mrs May’s position would be under threat.
Speaking on BBC One’s The Andrew Marr show, he said: “I think what will happen if the Government loses a vote is that there is potentially the chance of a change of Prime Minister, but I don’t think at that point they will want to give up as a Government, and I think the five-year parliament makes it possible for them to survive.”