Inside Westminster, it's clear Theresa May's fate is in the hands of people who are getting sick of her fast

“Just wait until we get a deal; it will change everything,” one close ally of Theresa May told me a week ago. He predicted the pound would rise, a relieved business world would endorse the deal and the momentum behind it would persuade wavering Tory MPs to support it in next month’s crucial Commons vote.

Things have not quite gone according to plan. The cabinet gave the deal only lukewarm support; two members and two junior ministers resigned. Business figures briefly welcomed the deal, but are now pressing on with preparations for the no-deal exit they are desperate to avoid. The pound has slumped.

May cut an isolated figure in the Commons when she tried to rally Tory MPs behind her deal, while Labour backbenchers gave no sign of rescuing her. The tide is running against, not for, the deal. Everyone at Westminster knows it will be shot down.

Even worse for May is the very real prospect that her critics will soon have the required 48 Tory MPs needed to trigger a vote of confidence in her as party leader. It could take place as early as Monday or Tuesday. If she failed to win a majority (158) of Tory MPs, she would have to resign, and could not stand in the ensuing leadership contest.

Although May allies believe she would win a confidence vote, it could be much too close for comfort. Such a ballot is secret. This matters because those on the government’s payroll – ministers, parliamentary private secretaries, MPs with party positions — can vote against May, which they cannot do in a Commons vote without resigning. If May survives a confidence vote, she cannot be challenged again for another 12 months. But this rule might persuade the MPs who have had enough of her and wanted her out after March – they are not confined to Eurosceptics – to act sooner. They might decide to try to oust her now rather than allow her another year (and perhaps to claim a mandate to stay on longer).

May would soldier on even if she won by only one vote. It would damage her if more than 100 oppose her (about third of Tory MPs). They would be voting against her deal, further proof it cannot clear the Commons hurdle.

Michael Gove’s decision not to resign is a much needed boost for May. If he had left, others would probably have followed, and it could have been the beginning of the end for May. That’s probably why Gove didn’t quit: after knifing his ally Boris Johnson during the 2016 Tory leadership contest and failing to win the crown himself, he does not want to be May’s assassin. That would not be a good look if he were ever to run for leader again.

Announcing he will carry on as environment secretary today, Gove pointedly avoided journalists’ questions about whether he supports the draft withdrawal agreement. He turned down the chance to succeed Dominic Raab as Brexit secretary because May would not allow him to seek a better deal. But Gove will now likely lead cabinet moves to persuade May to do just that – perhaps telling the EU the agreement will not win Commons approval unless the UK can unilaterally leave the “single customs territory” under the proposed backstop to prevent a hard Irish border.

The ministers promoting the deal on the media so far are loyalists such as James Brokenshire and Damian Hinds, rather than big hitters such as Sajid Javid and Jeremy Hunt. Their silence to date is ominous for May. She admits the backstop plan is difficult, even for her. On LBC radio this morning, she acknowledged fears that Northern Ireland could have different regulations to the rest of the UK. “We are looking at those … what we can do in the UK to help reassure the people of Northern Ireland,” she said.

Naturally, the EU is making clear the deal on the table is as good as it gets. It would say that, wouldn’t it? Perhaps May will have to endure the pain of losing the first Commons vote on the deal, to show the EU she has tried her best. Then, perhaps, the EU might tweak the withdrawal agreement. It might also offer May some help when the political declaration on the future UK-EU relationship is firmed up before the EU’s planned summit on 25 November.

May’s position is so perilous that we can’t yet be sure that meeting will go ahead. If she loses a confidence vote next week, the Brexit process would have to be paused while the Tories choose a new leader. An election would normally take two months but could probably be crunched into two or three weeks.

May is still alive, and we shouldn’t underestimate her ability to survive. Her nightmare is that, no matter how hard she works to sell her withdrawal agreement, her fate is not in her own hands. It lies with the cabinet, Tory MPs and then parliament. And none of them like her deal.