AS ever at Westminster, it’s a numbers game.

And at present, Theresa May doesn’t look as though she is anywhere near having the numbers to get her wobbly draft withdrawal agreement with Brussels through the House of Commons.

After what has been the most testing week of her premiership, the Prime Minister has survived; but only just.

A key moment came at 11.25am on Friday when Michael Gove issued a statement of support for his leader. It came against expectations at Westminster.

When, on Thursday night, the Environment Secretary turned down the role of Brexit Secretary because Mrs May had refused his request to be able to change the draft deal, it seemed the writing was on the wall.

How, if Mr Gove thought the deal needed to be renegotiated, could he possibly carry on?

Having been the "assassin" for his onetime chums Cameron and Johnson, what would it have said for his capacity for loyalty if the Scot had wielded the knife a third time?

By rallying round, Mr Gove helped shore up support for Mrs May, preventing the likes of fellow Brexiteers, Mordaunt, Grayling and Leadsom handing in their resignations.

Next week, the PM faces yet another challenge: the threat of a no-confidence vote. But the rebels, having expressed initial confidence they have the 48 signatures needed to spark a vote, appear increasingly diffident they can secure one.

And if Mrs May won any vote, her detractors could not challenge her for another year.

Tory whips will be busy this week ringing round colleagues, warning them against joining the rebellion, saying it could end with an even greater disaster: a Corbyn government.

Intriguingly, while London and Brussels have been adamant there can be no renegotiation of the draft agreement, Leave ministers like Gove, Leadsom, Mordaunt and Grayling are set to meet next week to see if they can push the Brexit door open a bit. There is even talk of the Pizza-clubbers Hunt, Hammond and Javid joining forces in the campaign.

The aim is to change the current backstop exit mechanism, which has so antagonised the pro-Brexiteers; namely, the UK can only leave the backstop with the EU27’s say-so.

The argument is if this could be amended in some way to allow – what in all other walks of life happens – free will so Britain could walk away at the moment of its choosing, then the draft deal just might make it through the parliamentary quagmire.

At present, the prospect of the draft deal getting through the Commons looks hopeless. It had been thought Mrs May could, given the tranche of Leave and Remain rebels, possibly rely on Labour moderates to push the Brexit withdrawal blueprint over the line.

But the Labour moderates as well as the opposition forces as a whole believe if the May deal is rejected, Britain’s sovereign Parliament could “take charge” and propose another vote with the option of staying in.

This is why the PM this week dropped into the public consciousness the three-way choice of her deal, a no-deal or a no Brexit.

As Labour figures begin to use more positive language about a People’s Vote, the SNP appear to be warming to it greatly too.

Yet, of course, there is also the little matter of indyref2 and when Nicola Sturgeon will make her big demand.

Earlier this week, much to the chagrin of some of her parliamentary colleagues, the First Minister again adopted a wait-and-see position; even though we now know the broad terms of the draft withdrawal agreement.

It seems clear, politically, Ms Sturgeon will make her call on the back of what she feels is the moment of maximum disruption for the Tory Government, which, at present, looks like the aftermath of the meaningful vote at Westminster.

But, everything to do with Brexit is a gamble. What if the PM won the vote?

In any case, Mrs May has said in the clearest of terms she would not facilitate another vote on Scotland’s future any time soon; it’s in the Tory manifesto.

But what if the PM lost that vote? Would she struggle on? Would she resign? Who would take over? Would there be a general election? Would Parliament succeed in tabling a motion for a People’s Vote?

Only one thing is certain: Britain’s Brexit nightmare would rumble on.