Four Brexiteer backbenchers have announced they will back the Prime Minister’s withdrawal agreement despite speculation they could vote against it.

In a possible sign that the tide is beginning to turn in favour of Theresa May’s controversial exit plan, Tory MPs including Sir Geoffrey Clifton-Brown and Sir Edward Leigh said they would support the government in the meaningful vote on Tuesday.

Former Public Accounts Committee chairman Sir Edward, who was appointed to the Privy Council last month, said it was “inconceivable” that Parliament and the Speaker John Bercow would allow the UK to crash out of the EU without a deal.

He said: “I will support the government on Tuesday in the meaningful vote. I think it is now inconceivable that this Parliament, and this Speaker, will allow the UK to leave on WTO terms on March 29.

“Therefore my message to my fellow Brexit-supporting MPs is you are playing with fire if you vote down this deal in the hope of something better, and the only way to deliver Brexit is to vote for the deal this week.”

He was initially an outspoken critic of May’s deal.

And senior backbencher Sir Geoffrey said that while he had “deep misgivings” about many aspects of the deal, it would, he believed, provide a “framework” to ensure the UK leaves on March 29.

He said: “While I retain deep misgivings about many aspects of the deal, in particular the open-ended nature of the backstop, the events of last week have clearly demonstrated that the Speaker and MPs who wish to remain in the EU will stop at nothing to prevent that happening.

“Whilst the deal is far from ideal it will create a smooth transition for business and jobs.

“Above all it will provide a framework to ensure that we actually leave on the 29th of March this year.”

Tory former minister Andrew Murrison said he also had reservations, but had decided to back the deal.

“After last week’s operation by the Speaker and hard-over Remainers to reverse Brexit and the prospect of more tricks to come, I’ve decided I have to back the Withdrawal Agreement so that we deliver on the referendum as promised.

“I’m still concerned about the EU’s unnecessary, politically inspired, Northern Ireland backstop. It must be ditched or time-limited if Brussels and Dublin are sincere about their future relationship with the UK.”

And Conservative MP for Sleaford and North Hykeham, Caroline Johnson, said: “As a Brexiteer I am unhappy with some aspects of the deal and had intended to vote against it.

“However I have come to realise that the Prime Minister is trying to deliver Brexit via a remain Parliament some of whom seem ready to go to any length to frustrate the referendum result and stop Brexit.

“We need to get this part of the process over the line so that we are out of the EU and Parliament can then refocus its efforts on the negotiations for our future relationship to ensure we seize the full benefits of Brexit.”