Nobody at Westminster expects Theresa May to win Tuesday night’s vote on her Brexit deal. But a wide range of outcomes are possible, and they will determine what happens next.

Under an amendment passed by increasingly rebellious MPs last week, May must respond to a defeat within three sitting days – by Monday 21 January. But her Commons statement will not necessarily offer a definitive plan B; she could say she is seeking further negotiations with the EU. The debate and vote on her motion would not have to take place on Monday, giving May a small window for further talks.

What, then, are the most likely outcomes of Tuesday’s vote, and what would follow?

The numbers game

More than 100 Conservative MPs have criticised May’s withdrawal agreement. On paper, if they and the 10 Democratic Unionist Party MPs, all voted against the deal, it would be defeated by around 200 votes. In practice, that will not happen. Some of the Tory critics have reluctantly decided to back the deal; a small number of Labour MPs have pledged support. So has one Liberal Democrat. May’s twin threats of a no-deal exit and “no Brexit” could persuade other critics to back her agreement or abstain.

So May might benefit from the “expectations game” if the defeat does not look so bad on the night.

Brexit so far: in pictures Show all 53 1 /53 Brexit so far: in pictures Brexit so far: in pictures Brexit campaign Boris Johnson led the VoteLeave campaign PA Brexit so far: in pictures Brexit campaign Boris Johnson MP, Labour MP Gisela Stuart and UKIP MP Douglas Carswell address the people of Stafford in Market Square during the Vote Leave Brexit Battle Bus tour on 17 May 2016. Their lead line on the tour was: “We send the EU £350 million a week, let's fund our NHS instead.” Getty Brexit so far: in pictures Voting day A man shelters from the rain as he arrives at a polling station in London on 23 June 2016. Millions of Britons voted in the referendum on whether to stay in or leave the European Union AFP/Getty Brexit so far: in pictures Referendum results Leader of Ukip, Nigel Farage, reacts at the Leave EU referendum party at Millbank Tower in central London as results indicated that it was likely the UK would leave the European Union AFP/Getty Brexit so far: in pictures Protesting the result A young couple painted as EU flags and a man with a sign reading “I’m not leaving” protest outside Downing Street against the voters decision to leave the EU on 24 June 2016 Getty Brexit so far: in pictures David Cameron resigns British Prime Minister David Cameron resigns on the steps of 10 Downing Street on 24 June 2016 after the results of the EU referendum were declared and the United Kingdom voted to leave the European Union Getty Brexit so far: in pictures Theresa May Becomes the new Conservative Party leader Theresa May receives a kiss from her husband Philip, after becoming the new Conservative Party leader on 11 July 2016. May became Prime Minister two days later and although she voted to remain in the referendum was keen to lead Britain’s Brexit talks after her only rival in the race to succeed David Cameron pulled out unexpectedly. May was left as the only contender standing after the withdrawal from the leadership race of Andrea Leadsom, who faced criticism for suggesting she was more qualified to be prime minister because she had children AFP/Getty Brexit so far: in pictures Lancaster House keynote speech on Brexit British Prime Minister Theresa May delivers her keynote speech on Brexit at Lancaster House in London on 17 January 2017. Where she spoke about her offer to introduce a transition period after the UK formally leaves the European Union in March 2019. Despite repeating the pro-Brexit mantra of “no deal is better than a bad deal”, the Prime Minister claimed she wanted a “tone of trust” between the negotiators and said Britain was leaving the EU but not Europe. She said there should be a clear double lock needed for the transitional period to make sure businesses had time to prepare for changes to their trading relationships with the EU Getty Brexit so far: in pictures Triggering of Article 50 British Prime Minister Theresa May in the cabinet, sitting below a painting of Britain's first Prime Minister Robert Walpole, signs the official letter to European Council President Donald Tusk invoking Article 50 and the United Kingdom's intention to leave the EU on 29 March 2017 Getty Brexit so far: in pictures Gibraltar nonsense Tensions have risen over Brexit negotiations for the Rock of Gibraltar. The European Council has said Gibraltar would be included in a trade deal between London and Brussels only with the agreement of Spain. While former Conservative leader Michael Howard claimed that Theresa May would be prepared to go to war to protect the territory. Spain's foreign minister stepped in only to assert that there was no need for the dispute Getty Brexit so far: in pictures Shock snap election Soon after triggering Article 50, Theresa May called on 18 April 2017 for a snap general election. The election would be on 8 June and it came as a shock move to many, with her reasoning to try to bolster her position before tough talks on leaving the EU AFP/Getty Brexit so far: in pictures Dissolution of Parliament for General Election Campaign Prime Minister Theresa May makes a statement in Downing Street after returning from Buckingham Palace on 3 May 2017. The Prime Minister visited the Queen to ask for the dissolution of Parliament signalling the official start to the general election campaign Getty Brexit so far: in pictures Conservatives lose parliamentary majority An arrangement of British daily newspapers showing front page stories about the exit poll results of the snap general election. British Prime Minister Theresa May faced pressure to resign on 9 June 2017 after losing her parliamentary majority, plunging the country into uncertainty as Brexit talks loomed. The pound fell sharply amid fears the Conservative leader would be unable to form a government AFP/Getty Brexit so far: in pictures Labour gains Britain’s opposition Labour Party leader Jeremy Corbyn gives a tumbs up as he arrives at Labour headquarters in central London on 9 June 2017 after the snap general election results showed a hung parliament with Labour gains and the Conservatives losing their majority AFP/Getty Brexit so far: in pictures Brexit negotiations begin Brexit Minister David Davis and European Commission member in charge of Brexit negotiations Michel Barnier address a press conference at the end of the first day of Brexit negotiations in Brussels on 19 June 2017 AFP/Getty Brexit so far: in pictures May speaks in Florence British Prime Minister Theresa May speaks on 22 September 2017, in Florence. May sought to unlock Brexit talks after Brussels demanded more clarity on the crunch issues of budget payments and EU citizens' rights AFP/Getty Brexit so far: in pictures EU council summit – insufficient progress German Chancellor Angela Merkel joins other EU leaders for a breakfast meeting during an EU summit in Brussels on 20 October 2017. The EU spoke about Brexit and announced that insufficient progress had been made AFP/Getty Brexit so far: in pictures DUP derails settlement on the withdrawal part of Brexit DUP Deputy Leader Nigel Dodds walks off after speaking to members of the media as a protester holding flags shouts after him outside the Houses of Parliament on 5 December 2017. British Prime Minister Theresa May was forced to pull out of a deal with Brussels after the DUP said it would not accept terms which see Northern Ireland treated differently from the rest of the UK Getty Brexit so far: in pictures May suffers defeat over EU (Withdrawal) Bill Theresa May suffers defeat in parliament over EU (Withdrawal) Bill on 13 December 2017. The Government was defeated by Conservative rebels and Labour MPs in a vote on its key piece of Brexit legislation. MPs amended the EU (Withdrawal) Bill against Theresa May's will, guaranteeing Parliament a “meaningful” vote on any Brexit deal she agrees with Brussels. Ms May's whips applied pressure on Conservative rebels who remained defiant in the Commons throughout the day and in the end the Government was defeated by 309 votes to 305 Brexit so far: in pictures EU council summit – sufficient progress Britain's Prime minister Theresa May arrives to attend the first day of a European union summit in Brussels on 14 December 2017. European leaders discussed Brexit and announced there was finally sufficient progress at the end of the two days AFP/Getty Brexit so far: in pictures The game moves to transition Brexit Secretary David Davis gives evidence on developments in European Union divorce talks to the Commons Exiting the EU Committee in Portcullis House, London, on 24 January 2018 PA Brexit so far: in pictures Trade deal is what May wants French President Emmanuel Macron gestures to Britain's Prime Minister Theresa May after they hold a press conference at the Royal Military Academy, Sandhurst, on 18 January 2018. May and Macron agreed a new border security deal, through which the UK will pay more to France to stop migrants trying to reach British shores on 18 January 2018 AFP/Getty Brexit so far: in pictures Transition period agreed The UK and EU agree terms for Brexit transition period on 19 March, 2018 Reuters Brexit so far: in pictures No agreement on Irish border The EU and UK however failed to reach an agreement on the Irish border during the successful talks on other Brexit issues AFP/Getty Brexit so far: in pictures EU attacks May’s ‘fantasy’ strategy For months after the March deal is struck there is little significant progress in talks. One senior EU official tears into Britain’s ‘fantasy’ negotiating strategy and accuses Theresa May of not even having a position on a variety of important issue Getty Brexit so far: in pictures UK releases Ireland plan Britain releases a new customs plan to solve the Northern Ireland border but Michel Barnier says it leaves ‘unanswered’ questions and would not prevent a hard border EbS Brexit so far: in pictures Chequers plan agreed The cabinet agrees on a plan known as the "Chequers deal" on July 6 2018. The plan seeks regulatory alignment on goods and food, divergence on services, freedom from the European Courts of Justice and an end to free movement. Many were surprised that the hard Brexiteers of the cabinet would agree to this plan PA Brexit so far: in pictures Chequers plan sparks resignations Brexit Secretary David Davis and Foreign Secretary Boris Johnson and numerous ministers resign in the days following the Chequers agreement Reuters Brexit so far: in pictures Davis out, Raab in On 9 July, Dominic Raab replaces David Davis as Brexit Secretary. Raab is a keen Brexiteer and was a housing minister before taking over from Davis Reuters Brexit so far: in pictures Barnier's "deal like no other" EU chief negotiator Michel Barnier claims on August 29 2018 that they are prepared to offer Britain a trade deal like no other, though he stressed that they will not divide or change the single market to accommodate Britain AP Brexit so far: in pictures "My deal or no deal" In an interview on Panorama on September 17, the Prime Minister insists that any Brexit deal will be offered to the EU on her terms. She asserts this amongst continued attacks on her approach to Brexit by Boris Johnson and the European Research Group, headed by Jacob Rees Mogg BBC/Jeff Overs Brexit so far: in pictures EU leaders reject Chequers Quite the blow was dealt to the Prime Minister at a EU leaders summit in Salzburg on September 20. European Council President Donald Tusk stated that the Chequers deal "will not work" Reuters Brexit so far: in pictures May demands respect Following the rejection of her Chequers plan the day before, the Prime Minister voiced her anger that the EU had dismissed it without offering an alternative. She stated that “throughout this process, I have treated the EU with nothing but respect. The UK expects the same. A good relationship at the end of this process depends on it." Getty Brexit so far: in pictures People's Vote march As the People's Vote campaign and The Independent's Final Say campaign gain traction, 700,000 people turn out in London to demand a final say on the UK's Brexit deal on October 20 2018 PA Brexit so far: in pictures More resignations As the Prime Minister settles on a Brexit deal, Brexit secretary Dominic Raab resigns along with Work and Pensions secretary Esther McVey and many other ministers Getty Brexit so far: in pictures Final Say petitions delivered to Downing Street People's Vote supporting MPs Chukka Umunna, Justine Greening and Caroline Lucas and The Independent editor Christian Broughton deliver over a million signatures in favour of a People's Vote to the Prime Minister at 10 Downing Street on December 3 2018 PA Brexit so far: in pictures May delays vote On December 10, the Prime Minister delayed the vote on her Brexit deal as it was near certain not to pass through the Commons due to Tory rebels and lack of DUP support AFP/Getty Brexit so far: in pictures No confidence motion Tory MPs triggered a confidence vote in the Prime Minister on December 12. She won by 200 votes to 117 Reuters Brexit so far: in pictures Commons rejects the deal Following the delay, the Prime Minister's deal was rejected in the Commons by a historic 230 votes AFP Brexit so far: in pictures Corbyn tables a no confidence motion Following the rejection of the Prime Minister's deal, opposition leader Jeremy Corbyn tabled a motion of no confidence in the government, which the government won by a margin of 19 AFP/Getty Brexit so far: in pictures Plan B The Prime Minister won the support of the commons to return to Brussels to renegotiate the backstop on January 29. In the same sitting, MPs also voted against a no-deal Brexit in a non-legally binding motion PA Brexit so far: in pictures EU council president savages Brexit campaigners who failed to plan for departure: ‘Special place in hell’ There is a “special place in hell” for pro-Brexit campaigners who demanded Britain leave the EU without explaining how it should happen, Donald Tusk has said. The European Council president launched the scathing attack as he accused anti-EU campaigners of pushing for Brexit “without even a sketch of a plan how to carry it out safely.” Mr Tusk also dismissed suggestions that the EU could reopen negotiations over the controversial Northern Ireland backstop, dealing a blow to Theresa May‘s hopes of securing fresh concessions as she tries to get her exit deal through parliament. Speaking in Brussels alongside Irish taoiseach Leo Varadkar, Mr Tusk said: “I’ve been wondering what a special place in hell looks like for people who promoted Brexit without even a sketch of a plan how to carry it out safely.” He also tweeted the accusation moments later Getty Brexit so far: in pictures EU and UK announce talks to restart after Theresa May visits Brussels Both have agreed to restart Brexit talks to find “a way through” the deadlock in Westminster, following a visit by Theresa May to Brussels. In a joint statement the British government and European Commission said Ms May had had a “robust but constructive” meeting with president Jean-Claude Juncker, and that the pair would meet again before the end of the month. But the EU again refused to reopen the withdrawal agreement and its controversial backstop – with any negotiations expected to focus on the future relationship between the UK and EU instead Getty Brexit so far: in pictures Brexit strategy lost MPs voted down May's Brext plans, with a majority of 45. The prime minister did not appear in parliament to see another defeat PA Brexit so far: in pictures Labour and Conservative MPs resign and create the Independent Group Back row of Chris Leslie, Gavin Shuker, Chuka Umunna and Mike Gapes, middle row of Angela Smith, Luciana Berger and Ann Coffey and front row of Sarah Wollaston, Heidi Allen, Anna Soubry and Joan Ryan PA Brexit so far: in pictures Non-biding votes on amendments to Brexit motion On February 27 he house held a series of votes, unanimously calling for the UK and EU to guarantee citizens rights in a no-deal scenario AFP/Getty Brexit so far: in pictures Attorney General publishes legal advice A hammer blow for May as Geoffrey Cox said her renegotiated deal can still leave UK in backstop against its will. Mr Cox did say the prime minister’s efforts had reduced the risk of the UK being trapped in the backstop indefinitely. MPs went on to vote against her deal by 391 to 242 UK Parliament/PA Brexit so far: in pictures No-deal off the table MPs rejected a no-deal Brexit by 43 votes on March 13, with cabinet ministers rebelling in another humiliating defeat for Theresa May. A day later they voted in favour of the prime minister seeking an extension to Article 50 AFP/Getty Brexit so far: in pictures House speaker bans May from third Commons vote on same Brexit deal John Bercow sensationally told Theresa May he would stop her making another attempt to pass her Brexit deal unless she has secured changes. The Speaker said a further ‘meaningful vote’ would be ruled out of order if the motion was “the same or substantially the same’ – under an ancient convention to stop the government bullying parliament on issues MPs have rejected Parliament Live Brexit so far: in pictures May writes to Tusk The prime minister wrote to Donald Tusk, president of the European Council, to ask for a three-month extension to give her more time to try to get her deal through parliament. However the European Commission advises the EU27 should offer a short extension to May 23 or a longer one meaning the UK would participate in European elections 10 Downing Street/AFP/Getty Brexit so far: in pictures European Council summit Theresa May’s request to extend triggering Article 50 until the end of June was rejected by the EU, and instead offered a shorter time frame. She accepted the offer of a delay until May 22 if her withdrawal deal is approved by Parliament. If MPs rejected it for a third time, the EU said Britain must propose a new plan by April 12. Ms May said she will not support a long delay because it would mean Britain participating in elections for the European Parliament Getty Brexit so far: in pictures Brussels confirms preparations for a no-deal Brexit are completed They warned that it is “increasingly likely” the UK will crash out. In a statement the European Commission (EC) said “preparedness and contingency work”, which the EC has been conducting since December 2017, was now finished. The announcement came days after EU leaders agreed to a request by Theresa May to extend the UK’s Brexit date AFP Brexit so far: in pictures May resigns British Prime Minister Theresa May reacts as she delivers a statement in London, Britain, May 24, 2019. REUTERS/Simon Dawson SIMON DAWSON Reuters

Crushing defeat

Defeat by more than 100 votes on such a flagship policy would normally see the resignation of a prime minister. But these are not normal times, and May would regard it as her duty to plough on. However, a three-figure margin would be humiliating, and would encourage MPs to try to seize control of the Brexit process – for example, by demanding a series of indicative votes on a possible plan B – including a Final Say referendum; a Norway plus arrangement inside the single market and a customs union; an EU-Canada-style free trade agreement and a “managed no deal”.

Supporters of the different options are keen for their plan to be “the last one still standing” after all the others have been rejected, so much will depend on how such indicative votes were held. If there is no majority for any alternative deal, the prospect of a referendum would increase.

After a crushing defeat, it would be harder for May to claim her deal could be amended and put to a second Commons vote after further EU concessions. The cabinet’s position would be important – although, like backbenchers, ministers are divided between a plan B deal involving a softer Brexit, and those willing to risk a no-deal departure. Ministers might finally call time on May’s deal, and persuade her to stage indicative votes and then adopt whichever came out on top.

May would probably need her own plan B to avoid having one imposed on her by the cabinet or Commons. After surviving a confidence vote as Tory leader last month, her Eurosceptic MPs cannot challenge her for another year. The threat to her is now from parliament. So she might try to build a majority with the votes of Labour MPs – perhaps by embracing a permanent customs union, something she has always opposed.

May could make a “managed no deal” the government’s central policy to honour her pledge to leave the EU on 29 March. But that would provoke cabinet resignations and MPs would likely find a way to block it.

Some ministers expect May to lose by between 70 and 100 votes. She could claim some momentum towards accepting her deal, and go to Brussels to seek improvements. She would probably get one more chance to put a revised deal to the Commons. The EU’s role will be critical in this scenario. EU insiders suggest they will be more flexible once parliament has voted on the deal, and might even reopen the withdrawal agreement. But they would first need to know what MPs would accept.

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As good as it gets

Some ministers believe that limiting the losing margin to under 70 votes would show that May’s deal is still alive. It’s the best she can hope for, and the expectations game would work in her favour. She would tell the EU that legally-binding guarantees that the backstop to prevent a hard Irish border is temporary, might secure a Commons majority in a second vote. May would be tempted to repeatedly put her amended deal to MPs until she got over the line.

Health warning

In a series of votes on Tuesday, parliament’s arcane procedures will be very important. Bizarrely, it possible that there is no specific vote on May’s deal, because MPs will first vote on amendments. Hilary Benn, Labour chairman of the Brexit select committee, has tabled one rejecting both a no-deal exit and May’s agreement. If passed, MPs would not vote solely on her deal. Benn is under pressure to withdraw his amendment as, if approved, it could minimise the scale of May’s defeat (as about 50 hardline Brexiteers will not vote against “no deal.”)

The other amendment to watch, tabled by Tory MP Andrew Murrison, would end the Irish backstop after a year in December 2021. Ministers are encouraging Tories to back it. Brussels has refused to put a time limit on the backstop; passing this amendment would put the ball back in the EU’s court.

The amendments, and the order in which they are voted on, will be selected by Commons speaker John Bercow, putting him back in the spotlight, after he was accused of anti-Brexit bias last week.

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Delay?

In the Commons today, May repeated her determination not to extend the two-year Article 50 process beyond 29 March. However, she might be forced to rethink once her deal is rejected. Even if she salvaged it in later votes, time would be running out to push through key legislation needed by exit day. MPs are likely to vote for the government to ask the EU to extend the time limit – not least to head off a cliff-edge departure.