UK Conservative Prime Minister Boris Johnson sent a request Saturday night to the European Union (EU) for an extension to the October 31 Brexit deadline, as he was required to do by the Benn Act, after losing a crucial vote in parliament.

However, the letter was unsigned and was accompanied by a second, signed letter, indicating Johnson believed a further delay would be a mistake.

At the first “Super Saturday” sitting of the House of Commons since the Falklands/Malvinas war 37 years ago, MPs voted in favour of an amendment tabled by Conservative MP Sir Oliver Letwin, withholding approval of Johnson’s Brexit agreement with the EU until all the necessary legislation had been passed.

The amendment’s specific intent was to ensure that Johnson would comply with the terms of the Benn Act. The latter gave him until 11 p.m. Saturday to dispatch a letter to the EU requesting a three-month delay in the UK’s leaving the Single European Market and Customs Union, given that Johnson’s proposed deal was not passed, in order to prevent a no-deal Brexit.

The Letwin amendment was passed by a 16-vote majority, by 322-306.

The motion on whether to back the deal as amended was approved by MPs without a vote because the government accepted defeat. This also meant that a cross-party amendment on holding a second referendum was not put to the vote.

Johnson declared immediately, “I will not negotiate a delay with the EU and neither does the law compel me to do so.”

This prompted Labour leader Jeremy Corbyn to warn that “The prime minister must now comply with the law,” and the Scottish National Party’s Westminster leader Ian Blackford to state that Johnson could face court proceedings.

Later, in a letter to MPs and peers, Johnson said: “I will tell the EU what I have told the British public for my 88 days as prime minister: further delay is not a solution. It is quite possible that our friends in the European Union will reject Parliament’s request for a further delay (or not take a decision quickly).” The UK would leave on October 31, he insisted.

In the end, Johnson ordered a senior diplomat to send an unsigned photocopy of the request for a delay and his own letter to European Council President Donald Tusk, stressing that “the Government will press ahead with ratification and introduce the necessary legislation early next week. I remain confident that we will complete that process by 31 October … [A] further extension would damage the interests of the UK and our EU partners, and the relationship between us.”

The next morning, Shadow Chancellor John McDonnell told Sky News that Johnson could “well be in contempt of Parliament or the courts” for sending his second letter.

The emphasis on legal action has been given impetus by the fact that the pro-Remain parties have secured only the most limited delay, the EU is less than enthusiastic about an extension and, if Johnson succeeds in passing his agreement, the UK leaves the EU on October 31.

The EU made the precariousness of the situation clear at a brief meeting of EU ambassadors Sunday morning, after which chief Brexit negotiator Michel Barnier said that the ratification process for Johnson’s agreement was continuing as “normal,” while Tusk consults with heads of state and government about a further Brexit delay. Barnier said that the passage of the Letwin amendment did not mean that the deal had been rejected.

French President Emmanuel Macron reportedly spoke to Johnson by phone, telling him a delay to Brexit “would be in no one’s interest.” The Republic of Ireland Taoiseach (Irish Prime Minister) Leo Varadkar said that the EU and UK had made a withdrawal agreement last Thursday that defends Ireland’s interests and that an “extension can only be granted by unanimity.”

If a delay is granted, which is still likely, it will therefore not be immediate and might have limits placed on it.

The government is now pushing for a speedy vote on Johnson’s deal, while the opposition is focusing on preventing one through tabling various amendments because the numbers indicate that it is likely to pass, now that a no-deal has been ruled out.

Letwin’s motion was supported by 10 former Tory MPs who had the whip removed or resigned over Brexit, including Philip Hammond, David Gauke and Amber Rudd. But Letwin, who has played a key role in formulating the Tories’ austerity agenda, and former Home Secretary Rudd have both made clear they will now return to the fold and back Johnson’s deal. Letwin said in parliament that the passing of his amendment was a “parting of the ways” with Remain campaigners. “I am behind the government now,” he said afterwards. “There will be no new Oliver Letwin amendments next week.” It is likely that all 10 will follow suit.

The Democratic Unionist Party’s 10 MPs voted against the amendment, but reportedly only decided to do so at the last minute, rather than abstain. Shadow Brexit Secretary Sir Keir Starmer made a public appeal yesterday to the loyalist sectarians to talk to Labour about backing a second Brexit referendum, pledging that “our door is open.” But how far the DUP will take its disagreement with Johnson is yet to be decided.

The most likely way that Johnson’s deal will pass is with the vote of Labour MPs from pro-Brexit constituencies. Six Labour MPs voted against the Letwin amendment and therefore with the government: Kevin Barron, John Mann, Caroline Flint, Kate Hoey, Ronnie Campbell and Jim Fitzpatrick. Three abstained: Melanie Onn, Rosie Cooper and Sarah Champion. All of these MPs are now expected to vote with the government, and others who did not, after the threats made by McDonnell of the “consequences” of defying a three-line whip, might follow.

Even if this is not the case, Johnson appears to have a majority of around five MPs.

In the short term, the government will attempt today to hold another “meaningful vote” on the deal, but the pro-Remain speaker of the House John Bercow is likely to disallow this. The next week will, therefore, be dominated by trench warfare over amendments, even as arch-Brexiteer Michael Gove declared, “We’re triggering Operation Yellowhammer to ensure if no extension is granted, that we have done everything possible to leave without a deal.”

Operation Yellowhammer includes plans to utilise the police and army against protests, strikes and civil unrest provoked by the economic impact of a no-deal Brexit.

Corbyn has now been all but wholly replaced as spokesman for Labour’s Brexit policy by McDonnell. Corbyn’s call for a general election and a renegotiation of Brexit by Labour prior to a second referendum, which is official party policy agreed at congress, is largely ignored.

McDonnell was the featured speaker at yesterday’s demonstration in London calling for a Final Say on Brexit that attracted hundreds of thousands, where he rubbed shoulders with leading Blairites involved in plotting Corbyn’s removal, pro-remain Tories, and Liberal Democrats demanding a second referendum and a government of national unity to implement it. He told Sky News Sunday, “If Boris Johnson is confident about this deal, put it to the people.”

Starmer has gone even further in seeking to rule out a general election, suggesting on the BBC’s Andrew Marr Show that Labour could back Johnson’s deal provided that the Tories commit to a second referendum in which the deal is put up against an option to remain in the EU.