Theresa May will face her internal party critics on Wednesday as she battles to keep her Brexit plans on track.

The Prime Minister will attend a meeting of the Conservative backbench 1922 Committee in Parliament just days after one anonymous opponent suggested she should “bring her own noose” to the gathering.

A senior Tory source said Mrs May was “taking the opportunity to talk to colleagues” at the 1922 Committee meeting.

Confirmation of her attendance came amid reports that the number of Conservative MPs submitting letters calling for Mrs May’s removal was approaching the 48 needed to trigger a no-confidence vote in her leadership.

In an indication of the scale of opposition her Brexit plans face, the number of Tories backing a social media campaign opposed to the Chequers blueprint reached 50.

The Stand Up 4 Brexit campaign, which has received high-profile support from former foreign secretary Boris Johnson, said Sir Edward Leigh had become its 50th backer.

However, there were signs that a series of lurid briefings over the weekend by unnamed backbenchers calling for her to be “knifed” had backfired, causing MPs to rally behind her.

Andrew Mitchell – an ally of former Brexit secretary David Davis who is seen as a possible leadership contender – said a challenge to Mrs May would be a “mistake”.

Cabinet meeting
Brexit Secretary Dominic Raab leaving Number 10 after Tuesday’s Cabinet meeting (Kirsty O’Connor/PA)

The Prime Minister’s decision to attend the private meeting comes after she ordered ministers to prepare weekly updates on preparations for Brexit – either with or without a deal.

The updates will be delivered at the regular Cabinet meeting by Brexit Secretary Dominic Raab, who told ministers on Tuesday that “good progress” was being made on preparing for both possibilities.

The meeting came as the Prime Minister faced increasing pressure for a breakthrough in talks with the EU, after last week’s summit ended with no deal.

Mrs May told MPs on Monday that the terms of Britain’s withdrawal from the EU were 95% agreed, but the “sticking point” remained the issue of the Irish border.

However, she came under fire from critics on all sides in the Commons after she confirmed that she could accept a short extension to the transition period after the UK leaves in order to secure a final settlement.

The PM told Tuesday’s Cabinet meeting in 10 Downing Street that preparations for the no-deal scenario continue to be “essential”, but stressed that the Government’s priority is to secure a deal.

Cabinet meeting
Ministers Claire Perry, Greg Clark and David Gauke leaving 10 Downing Street after the Cabinet meeting (Kirsty O’Connor/PA)

She told ministers that European Council president Donald Tusk had declared himself ready to call a special Brexit summit if there was “decisive” progress in negotiations, which continue at official level in Brussels.

The Government was working “intensively” to find a way forward on the issue of the backstop which the EU is demanding to keep the Irish border open, she said.

Irish broadcaster RTE reported that the EU is ready to agree the UK-wide backstop proposed by Mrs May, but only as part of a separate treaty following a withdrawal agreement including a backstop applying to Northern Ireland only.

But Mrs May’s official spokesman said: “The prospect of Northern Ireland being placed in a different customs arrangement to the rest of the UK is unacceptable.”

Irish premier Leo Varadkar has said he has “every confidence” that the UK Government will not want to move away from its commitments to the backstop agreement.

“From our point of view, what Ireland is looking for is what we have always been looking for from day one and what has been committed to by us and the UK Government in principle and in writing on a number of occasions now,” said Mr Varadkar.

“That is, we have a backstop that gives us an assurance that there will be no hard border on the island of Ireland no matter what happens, that that backstop is legally operable and that applies unless and until there is a new agreement.

“That is something that the UK Government has committed to in principle, committed to in writing, and I have every confidence that the UK Government will honour that commitment.

“Britain is an important country, a serious country, a great country with great history. I don’t think they will want to be moving away from their commitment.”

In the Commons on Monday, both Tory Brexiteers and Remainers expressed concern that a backstop deal could leave the UK trapped indefinitely in a transitional arrangement with no say in the rules governing it.