With her deal left in tatters, and facing a no-confidence motion from Labour leader Jeremy Corbyn, what are PM’s options, asks Sherelle Jacobs
There is a huge range of possible outcomes now that MPs have voted 'no' to Mrs May's Brexit deal - these broadly include no deal; a "managed" no deal; a pivot to a Norway-style relationship; a second referendum; a general election; or a second vote of some kind, perhaps after a renegotiation phase with Europe. The only certainty is that in the absence of any other action by parliament or the government, the UK will leave the European Union on March 29, 2019.
1. Will Theresa May resign?
It is unclear whether a prime minister can survive having lost such an important piece of legislation on such a crushing scale. Clearly her authority has been severely damaged.
She could choose to resign, or to fight on - a possibility given the lack of an obvious consensus in the Tory Party around an alternative candidate.
Should she choose to resign, the party will be looking for new leadership, but the time taken to complete a contested leadership election will probably require the UK to ask for a temporary extension of Article 50.
2. She strikes a deal with Labour
Presuming she survives Corbyn's no-confidence motion (and it seems likely she will), the prime minister could soften her deal to win over the significant number of Labour MPs who favour something more along the lines of Norway-plus. But this scenario raises various questions.
Firstly, will Eurosceptic Corbyn, who has thus far avoided pinning his colours to any particular policy, be willing to get behind a softer Brexit? Especially one that will annoy both Labour Leave voters and the party's grassroots, who are calling for a second referendum.
It is unclear whether Mrs May would be able to secure a special permanent customs union arrangement tailored to the needs of Great Britain, as proposed by Jeremy Corbyn, although EU officials have signalled the EU would be willing to talk on this.
What about the backstop? With a Norway-style deal, which would definitely require the UK to accept free movement, it would still be an issue. The DUP might walk out of the government in disgust, causing the latter's collapse.
3. Her Plan B is actually no deal
Although those close to the prime minister believe that the PM would never willingly commit to no deal, it is arguably one way to both break the stalemate in parliament and ensure her own survival.
True, there is currently no majority for no deal in parliament. But the prime minister could opt for the 'nuclear option' - attaching a vote of confidence in the government to the no-deal vote.
In other words, voting down no-deal would automatically lead to the collapse of the government.
It is a high-risk strategy, but such action by the PM could call the bluff of Tory Remainer rebels. Crucially, since there is currently a majority in parliament against no deal, there is no majority for a single alternative. The Remainers are stuck.
With support from Tory Brexiteers, more ambivalent Tories, Leave-backing Labour MPs like Kate Hoey, as well as the 10 DUP MPs, no deal could scrape together just enough support to get across the line.
4. May lets Parliament vote on a new Brexit plan
To recap, MPs are claiming that Parliament has 'taken back control' of Brexit from the executive following a successful rebellion led by Conservative Remainer Dominic Grieve.
According to Grieve's successfully tabled amendment, the PM now must come up with an alternative plan within three days of her deal being defeated, which parliament could then amend. Technically, the amendment is merely advisory and the government could ignore it, but politically that may prove very difficult.
As it stands, parliament is clearly hungry for more say over Brexit, there is no majority in parliament for any one deal, and Theresa May is determined to cling on to her own proposal.
Her Plan B may thus be to allow parliament to debate and vote on all the options on the table in turn, in a series of so-called 'indicative' votes - namely EEA membership, no deal, a second referendum, and her own deal (perhaps whilst seeking to renegotiate aspects of it with the EU).
It could be one way to run the clock down and keep her own deal in play, before trying to ram her deal through for a second time at the last minute - a classic Theresa May strategy.
5. Labour wins/loses its motion of no confidence
Jeremy Corbyn tabled a no-confidence motion in the government within minutes of last night's result. On the one hand, the vote could help inflict further damage on Theresa May, which could cause her to resign, which could cause the Tories to go into further meltdown - no bad thing for Labour in the short term.
But the downside for Corbyn is that Labour seems unlikely to win a no-confidence motion, as the DUP has given no indication that it would ever vote in a way that would help a Corbyn government to power. And once a confidence vote is out of the way, the calls from the Labour grassroots for Corbyn to get behind a second referendum could become deafening.
In the event that Labour, against the odds, does win a no-confidence motion, then the race for the Tories to try to form another government that commands the confidence of the House begins.
6. MPs stop Brexit by revoking Article 50
Such a path is favoured by Remainers who would like to stop Brexit without having to bother with the messy, democratic business of a second referendum. It should not be discounted in the event that Theresa May fails to come up with a Plan B within three days.
There is also some talk in the Commons that moderate MPs might vote to revoke Article 50 as a means of stopping the clock to allow renegotiation of the deal, or more time to prepare for a no deal.
The problem is that the EU may be able to veto the revocation if it suspects "abusive practice" - and using the tool to stop the clock, or buy the government more time might be deemed as such.