Michael Howard, Conservative leader between November 2003 and December 2005, stated Mrs May’s premiership is only safe for the “next few months”, and is dependent on her securing a final Brexit deal with the EU and the House of Commons.
However, he also admitted the Prime Minister is the right person to lead the country through the fractious Brexit negotiations over the coming months.
Speaking at the Gadson Club, an alumni meeting for former members of the Oxford University Conservative Association, Mr Howard is heard saying in a recording obtained by The Sun: “I think she’s the right person to take us through the next few months.
“There’s a second part to my answer. In March 2019, everything will be different, and I don’t know how they’ll look.
“She could then be in a very strong position. She might, despite all the odds, have negotiated a Brexit which has got through Parliament.”
He argued Mrs May would then be due a “great deal of credit” and may lead the Conservative Party into the next General Election if she does manage to secure a Brexit deal.
However, he argued Mrs May’s political future depends on the conclusion of the Brexit negotiations in March 2019.
The former MP and Conservative peer said: “In which case, I think she would be entitled to a great deal of credit, and her position would be much stronger than it appears to be now, and then she might well go on to take us through to the next election.
“On the other hand, it’s a possibility she may not be quite as rosy in March 2019.
“So what happens after March 2019 depends on where we are in March 2019.”
Mrs May is also likely to face opposition from another former Tory leader, Sir John Major, who will outline his opposition to Brexit alongside former Foreign Secretary David Miliband this evening.
Speaking previously about the Brexit negotiations on BBC’s Andrew Marr show, he said: “If we crash out without a deal, the people who have least are going to be hurt most.
“It would be a terrible betrayal of the interests of everyday people, who really are not political.”
The Prime Minister was nevertheless defended by Foreign Secretary Jeremy Hunt, who warned it is “one of the biggest mistakes that anyone can make” to underestimate Mrs May.
Speaking to Sky News ahead of a UN meeting, he said: “After that very difficult General Election, some people didn’t appreciate the steel at the heart of that lady.
“We are led by someone very tough and very resilient and now I think people in Europe are begging to realise the same.”