Britain's parliament last month demanded that Prime Minister Theresa May renegotiate a Brexit divorce deal that the other members of the European Union say they will not reopen.
With just six weeks until the United Kingdom is due by law to leave the EU, the options include a disorderly Brexit, a delay to Brexit or no Brexit at all.
Mrs May's hope of presenting a united front to convince Brussels to make changes to the deal suffered a heavy blow yesterday when both eurosceptic and pro-EU politicians in her party refused to endorse her approach, condemning her to defeat in parliament.
Below is a summary of what is due to happen next:
"High Noon"- 27 February
Despite the Valentine’s Day defeat, Mrs May has promised she will continue to try and renegotiate the deal with the EU.
If parliament has not approved a deal by 26 February, she will make a statement updating politicians on her progress on that day and lawmakers will have an opportunity on 27 February to debate and vote on the way forward.
Several Conservative politicians, including some ministers, have indicated this will be the last chance they give her to find a way through the impasse.
Opposition Labour Party MP Yvette Cooper plans to use that debate to seek support for legislation that would force the government to decide between leaving without a deal or extending the Article 50 negotiation period if it has not had a deal approved by 13 March.
Vote on a revised deal - February/March
Mrs May said the government would bring a revised deal back to parliament for a vote as soon as possible.
Before the previous vote, parliament held five days of debate but it is not clear whether there would be another lengthy debate before any subsequent vote.
Mrs May is required by law to get parliamentary approval for any exit deal.
EU summit - 21-22 March
EU leaders are due to meet in Brussels. This could be an opportunity for an eleventh-hour deal or it would be the last chance to agree an extension of the Article 50 negotiation period and delay Brexit to avoid no-deal disruption.
If the summit goes badly and there is still no deal in sight then Mrs May will have to decide whether to delay or go for a no-deal Brexit.
Last weekend – 23-24 March
If a deal is seen as viable at the summit, officials could work through the weekend to nail down the details with a final deal - and a possible extension to 30 June conditional on British parliamentary approval - announced on Sunday 24 March - Monday 25 March .
Final week - 25-29 March
If a deal could be clinched, then the British parliament could vote on it, possibly on 26 March. The European Parliament could ratify the deal that week.
Exit day – 29 March?
If Mrs May does not get a deal approved by parliament by 29 March, Britain faces a disorderly exit, or may be forced to seek an extension of Article 50 to give more time to reach an agreement. It is not certain the EU would agree to this.
Some politicians, including Labour leader Jeremy Corbyn, have said it is now "inevitable" that the government will have to seek an extension, as there will not be enough time to pass the necessary legislation for Britain's exit before 29 March.
The leader of Britain's lower house of parliament, Andrea Leadsom, has said the date might need to be pushed back by a couple of weeks.
European Parliament elections
The bloc will vote to elect a new European Parliament on 23-26 May. The new chamber would sit from 2 July, a date that is shaping up to be the EU's limit for any extension of Article 50.
The EU says Britain would have to organise European Parliament elections on its soil if it were to delay Brexit beyond that as otherwise its people would be deprived of their democratic representation while still being in the EU. The bloc fears Britain would not do that.
Some in the EU also fear that, should Britain vote, it would elect a staunchly eurosceptic representation to the European Parliament that is already expected to have a larger contingent of EU critics influencing the bloc's policies.
The main centre-right group, whose leaders include German Chancellor Angela Merkel, could also lose its place as the biggest in the European Parliament; UK Labour seats could help the European Socialists overtake the People's Party, from which British Conservatives broke away to sit separately.
Delayed Brexit – 30 June
If a Brexit extension is sought, one date being talked about in Brussels is 30 June, the Sunday before the new European Parliament sits at 10am (9am Irish time) on 2 July.
Some argue for an exit before 23 May, the day Britain would otherwise be due to hold an EU election.
