Theresa May will brief the Cabinet on the progress of the Brexit negotiations after last week’s Brussels summit failed to achieve the hoped-for breakthrough.

The Prime Minister told MPs on Monday the terms of Britain’s withdrawal from the EU were 95% agreed but that 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.

Both Tory Brexiteers and Remainers expressed concern that it could leave the country trapped indefinitely in a transitional arrangement with no say in the rules governing it.

Brexit
Liam Fox has said a leadership challenge would be utter folly (Kirsty O’Conor/PA)

The latest display of backbench unrest came amid reports that the number of Conservative MPs submitting letters calling for her removal was approaching the 48 needed to trigger a no confidence vote in her leadership.

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

International Trade Secretary Liam Fox – a prominent Leave campaigner in the referendum – warned it would be a mistake for MPs to move against the Prime Minister at a crucial moment in the Brexit talks.

“We are in a process of negotiation. It would seem to be an act of utter folly to change the Prime Minister at this point,” he told Sky News during a visit to New York.

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

“I think it is right to give the Prime Minister every support to conclude a deal,” he told BBC2’s Newsnight.

However, he warned Mrs May could struggle to get the support of the House of Commons for any agreement she brings back from Brussels.

“There is a danger tonight it seems to me that Parliament won’t accept that deal or any other deal. That will be a serious problem,” he said.

There was further respite for Mrs May when the leading Tory Brexiteer Steve Baker announced he was withdrawing amendments to the Northern Ireland Bill designed to prevent the activation of the so-called Northern Ireland “backstop” – intended to ensure the border remains open after Brexit.

The former Brexit minister – who quit over Mrs May’s Chequers plan for leaving the EU – later welcomed her “strong assurance” in the House on maintaining the integrity of the UK.

The Prime Minister told MPs she could not accept the EU’s original backstop plan as it would mean imposing controls on goods traded between Northern Ireland and the rest of the UK, creating “a customs border down the Irish Sea.”

While she was ready to explore “every possible option” to break the impasse, she said a “critical” first step should be a legally-binding agreement on a temporary UK-EU joint customs territory to avoid the need for a Northern Ireland-only backstop.

As an alternative, if at the end of the transition at the end of 2020 a deal on the UK’s future relationship with the EU was not quite ready, she said it might by preferable to prolong the transition.

However, she stressed any such extension would have to be for a short time only and would have to be over “well before” the scheduled end of the current parliament in May 2022.