Theresa May could still press pause on Brexit meaningful vote

It is meant to be a watershed week; the moment when Theresa May - after two years of negotiating in Brussels, Westminster and within her own cabinet - asks parliament to back her Brexit deal.

But just hours from the planned meaningful vote it is far from clear whether it will go ahead at all, in the face of what is looking like a catastrophic defeat that threatens to bring down her premiership - and her government too.

Senior sources have told me that the vote is going ahead "as it stands" but say in reality the prime minister and her chief whip have not made the decision yet as to whether to postpone vote or not.

I'm told her inner circle are likely to make the final decision on Monday night after the fourth day of debate on her Brexit deal in the Commons.

There are various options that the prime minister's team are weighing up as we go into a critical week for Mrs May - and for the country too.

:: May battles to keep Brexit deal alive as opponents circle

The first question they are surely asking is how big will the defeat be and what could then flow from a hundred-plus rebellion on the Tory benches?

A catastrophic defeat will undoubtedly plunge her premiership, already hanging by a thread, into a full-blown crisis.

Labour leader Jeremy Corbyn could seize on the mayhem and table a motion of no confidence in her government as early as Tuesday night.

It is hard to see how Labour could actually get such a vote across the line given it would rely on the DUP voting with republican Corbyn over unionist May.

But there is a very slim chance of a defeat - and that could bring about a Labour/SNP minority government by Christmas, although some Labour sources tell me its more likely that Mr Corbyn will table a censure motion instead.

This is designed to express in the strongest possible terms disapproval in the prime minister or in her government.

The DUP are far likelier to go for this - perhaps hoping to help oust Mrs May as Conservative leader - then move with Labour to bring the Tory government down.

A huge defeat could also, from her own party, precipitate a confidence vote in her leadership.

There has already been one failed coup in the last month, but some in the party feel that a resounding defeat on her landmark policy has to result in her departure as PM and would-be successors - Boris Johnson, Dominic Raab, Esther McVey - were lining up this weekend to offer their own Brexiteer pitch to the party as they circle the prime minister.

But Mrs May also has to consider what might happen with both her DUP and Brexiteer colleagues on Tuesday if she did - against the odds - win the vote, points out one senior source.

Brexiteers might be so furious that they would trigger a confidence ballot anyway, while the DUP might be so furious that they do back Mr Corbyn to bring her down.

After all, her confidence and supply partners have made it clear they cannot support the government if the Brexit deal goes through as it stands. That means Mrs May must find more concessions if she wants to remain in No 10.

Which brings me neatly to No 10's Plan B. And that isn't whether to back a Norway style Brexit or pivoting to a second referendum - yet.

It is rather what Mrs May could try to do in the coming days to win over support for her deeply unpopular deal.

One option is - as her Brexiteers and the DUP keep telling her - to return to Brussels to seek more concessions.

A source tells me Mrs May could postpone the deal and return ahead of the European Council summit on Thursday for emergency talks with Donald Tusk and Jean-Claude Juncker.

"It's not impossible she will go early to try and negotiate ahead of the council," said one figure, pointing out that colleagues who have publicly opposed the deal need something to help them climb back down the ladder

This could be a time limit on the backstop or a unilateral exit clause. Both will be supremely difficult to negotiate.

Another option might be to use parliamentary procedure to avoid a crushing defeat.

MPs will vote on up to six amendments to the meaningful vote before Mrs May's plan is voted on and a couple of them - if selected by the Speaker - could kill off the prime minister's motion.

The one to watch is an amendment laid by the chair of the Brexit select committee, Hilary Benn. He has drafted an amendment that blocks both a no-deal Brexit and kills off Mrs May's motion.

If passed, it would stop the meaningful vote even taking place and has the advantage of avoiding an enormous defeat, as it would be Remainers such as former attorney general Dominic Grieve who might vote for this rather than the Brexiteers.

The scale of her defeat could fall back from 100 plus to under 20.

But it does kill off her deal, which is something she will not want to happen.

With options like these, it might be better to press pause and there have been a couple of clues in the past week that No 10 is laying the ground for a dignified retreat.

One came on Thursday when the submarine-like Sir Graham Brady, chair of the powerful 1922 backbench committee, surfaced to urge the prime minister to delay the deal, saying "most of us would like to see an agreement being reached" but that this would require more time.

The other clue was the collapse of the much-vaunted TV debate between Mrs May and Mr Corbyn, originally scheduled for Sunday night.

Called off after the two party leaders disagreed on the format and channel for the head-to-head, it also means Mrs May hasn't nailed her colours to the mast with the public should she decide to pull the vote at the 11th hour.

There is perhaps one thing her team are sure of as they enter into uncharted political and constitutional waters this week - those around her remain convinced the prime minister will not resign, no matter what.

Of course, MPs may try this week to take that decision out of her hands, all the more reason to avoid a crushing - perhaps fatal - parliamentary defeat.