Under UK law, the House of Commons must pass the divorce deal (officially known as the Withdrawal Agreement) for it to have effect.

But in January, it was defeated by 432 votes to 202. Pro-Brexit Conservative MPs allied with Labour to deliver one of the biggest losses for a British government in political history.

May promised to get legally binding changes to the deal, to satisfy at least some of the objections of pro-Brexit MPs.

So – with just two weeks until the legislated date of Brexit, March 29 – what now?

Tuesday, March 12: Second Meaningful Vote

May is relying on the looming Brexit deadline to swing wavering Brexiters onto her side, claiming that if they don’t back her deal, the UK “may never leave” the EU.

But hardline Brexiters and Labour say they will vote against this deal for the same reasons they voted against the same deal last time.

May has held out the prospect of a last-minute concession from the EU to woo Brexiters, but it is unclear at the time of writing what she will deliver.

If May wins, against the odds, then it will be all hands on deck for Brexit. The UK might need a short ‘technical extension’ from the EU to dot legislative i’s and cross t’s.

There might be a twist. The government has toyed with the idea of a vote on a hypothetical ‘improved’ deal it has yet to agree with Brussels. This would really annoy many MPs by stretching the word “meaningful” beyond its normal use. It would also likely be received with incredulity in Brussels, and amount to little more than a prelude to a third, ‘real’ Meaningful Vote before the end of March.

Wednesday, March 13 – No Deal Vote

Assuming the Meaningful Vote is held and lost, May has promised Parliament a vote on leaving the EU without a Withdrawal Agreement – the so-called ‘no deal' Brexit.

Parliament has already voted against a 'no deal' Brexit in a non-binding amendment to a previous motion, and is likely to do so again.

But this vote has no legal effect. It just expresses Parliament’s will for the next step – and focuses minds on the consequences.

Thursday, March 14 – Brexit Delay Vote

If the Meaningful Vote is lost, but Parliament doesn’t want a 'no deal' Brexit, then on Thursday it will, May has said, get a vote on a “short limited extension” to the Brexit date of March 29.

Downing Street believes that if Parliament votes down ‘no deal’ then it will, logically, agree to an extension.

But politics doesn’t always follow a logical path.

If the extension is voted down, then May could take the politically (and legally) risky move of seeking an extension anyway. This probably wouldn’t fly, as Parliament has to change the date on Brexit legislation due to swing into effect on March 29.

More likely, without a vote for an extension, there will be a ‘no deal’ Brexit.

If there is an extension, then at some point the UK has to go through all this again.

The 'no deal' scenario

In February, the UK government published a 12-page ‘No deal assessment paper’, sketching the consequences of a no-deal Brexit.

It revealed that a third of the government’s “most critical” no deal preparations were not on track (it didn’t say which ones). This includes many trade agreements between the EU and third countries, including major trading partners such as Japan and Turkey, which have not yet been rolled over into UK-specific deals.

The report found there is “little evidence that businesses are preparing in earnest for a no-deal scenario”, with small and medium businesses particularly unready.

For example, just 40,000 out of an estimated 240,000 importing businesses had registered for a trading ID system that would allow them to import goods from the EU after a no-deal Brexit.

The government estimates a GFC-level 9 per cent hit to the UK economy after 15 years from a no deal Brexit, not including short term disruptions “which would be likely to have additional short and long-run economic impacts”.

Almost a third of the UK’s food supply comes from the EU. Some food prices are likely to increase and there is a particular risk of shortages of fresh fruit and vegetables.

The UK’s agricultural industry would be particularly hurt, as the EU would immediately apply tariffs of 70 per cent on beef and 45 per cent on lamb imports (more than 90 per cent of Welsh lamb exports go to the EU). And the UK automotive industry would suffer a painful, possibly existential blow.

The extension scenario

The UK must win the agreement of all 27 EU member nations to delay the Brexit date.

That might be tricky. Many are fed up with the Brexit distraction from urgent issues such as migration, re-emerging nationalist dissent, a stumbling economy and the upcoming EU Parliament elections.

Rather than just stretching out the deadlock, the EU might demand a new referendum to assess support for the Withdrawal Agreement and its alternatives.

French President Emmanuel Macron, for example, has said he would veto any delay to Brexit without a “clear objective” based on a “new choice” by the British.

Any extension beyond mid-2019 hits another problem: the EU Parliament elections in May. If the UK is still in the EU, this could prove a legal and political minefield.

Wild card one: A second referendum

What Will Jeremy Do? Labour has said its biggest priority is to get into government and negotiate a softer alternative to what it has dubbed the “Tory Brexit”.

Labour leader Jeremy Corbyn only reluctantly and recently announced that Labour is also now behind the idea of another referendum – an option Labour members enthusiastically endorsed last year.

But it is unclear when Labour would actually vote for one – and it doesn’t stand a chance until they do. Shadow chancellor John McDonnell said Labour would “use this week to kill off no deal”. After that they would seek “a realistic deal or going back to the people [for a second referendum]”. He was vague on the timeline.

It is also unclear if there is enough support in Parliament to get a second referendum across the line even then, especially as some Labour MPs would likely defy their leader to oppose it.

A second referendum would take months to organise and require a delay to Brexit.

Wild card two: A general election

The government’s support in Parliament already hangs on a knife edge. A looming chaotic Brexit could be the cue for a general election, with or without a delay to the Brexit date.

Or the government might call an election to rally voters behind a prime minister who has clearly lost the support of Parliament on her most important project.

Theresa May is immune from an internal party challenge until the end of the year, but she might still quit, deciding she doesn’t want to be the 'no deal' Brexit PM, or persuaded by colleagues to go of her own accord.

If so, her party could end up in hardline-Brexit hands – this, too, could trigger an election. Or it might mean a delay and fresh negotiations in Brussels.