MPs have inflicted a humiliating defeat on Boris Johnson by passing a backbench amendment withholding their support from his Brexit deal.
Instead of backing Johnson’s agreement in a “meaningful vote”, MPs passed an amendment tabled by a cross-party group of MPs led by Oliver Letwin by 322 votes to 306 – a majority of 16.
The prime minister said he was not “daunted or dismayed” by the defeat, and would press ahead with tabling Brexit legislation next week. MPs are likely to take the opportunity to table a string of amendments, including on trying to force a second referendum.
The move by cross-party MPs was aimed at forcing Johnson to comply with the terms of the Benn act, which obliges him to write to the EU to request a Brexit delay, if he had not won approval for his deal by 11pm.
But Johnson insisted: “I will not negotiate a delay with the EU, and neither does the law compel me to do so” – a claim that is likely to see him face a legal challenge.
The Labour leader, Jeremy Corbyn, said: “The prime minister must now comply with the law. He can no longer use the threat of a no-deal crash-out to blackmail MPs to support his sellout deal.”
The clashes came during a historic Saturday sitting of parliament, during which the PM adopted an emollient tone as he implored MPs to throw their weight behind his deal.
“Let us come together as democrats behind this deal, the one proposition that fulfils the verdict of the majority but which also allows us to bring together the two halves of our hearts, to bring together the two halves of our nation,” he urged them.
“Let us go for a deal that can heal this country and allow us all to express our legitimate desires for the deepest possible friendship and partnership with our neighbours. A deal that allows us to create a new shared destiny with them.”
But the shadow Brexit secretary, Keir Starmer, vehemently rejected Johnson’s arguments in a forensic speech highlighting the deal’s differences with Theresa May’s withdrawal agreement, including the absence of legal guarantees on workers’ rights.
Starmer concluded: “The deal before this house is a thoroughly bad deal for jobs, rights and living standards, a bad deal for the future direction of this country – it will put us on the path to an entirely different economy and society: one of deregulation and divergence.”
“Manufacturing having been on its knees, and now having revived at least in part, how anyone could take an axe to it I will never understand. If we pass this deal today it will be a long way back for the communities we represent.”
Letwin said he was minded to support Johnson’s deal, but the aim of his amendment was “to keep in place the insurance policy provided by the Benn act, which prevents us from crashing out automatically if there is no deal by 31 October”.
Johnson hinted in his speech before the vote that EU leaders could rebuff any British request for a delay. “I must tell the house in all candour that there is very little appetite among our friends in the EU for this business to be protracted by one extra day,” he said.
He told MPs: “Whatever letters they may seek to force the government to write, it cannot change my judgment that further delay is pointless, expensive and deeply corrosive of public trust.”
A spokeswoman for the European commission said it was up to the UK government to make the next move after the developments in the Commons.
She said: “The European commission takes note of the vote in the House of Commons today on the so-called Letwin amendment meaning that the withdrawal agreement itself was not put to vote today.
“It will be for the UK government to inform us about the next steps as soon as possible.”
A spokesman for the European council president, Donald Tusk, declined to comment. Ambassadors for the EU27 will meet on Sunday morning to discuss the latest developments.
After being defeated on the amendment, the government and opposition agreed not to hold a vote on the amended motion, which Downing Street sources said they considered “meaningless”.
The leader of the House of Commons, Jacob Rees-Mogg, then told MPs the government would seek to hold another meaningful vote on Johnson’s deal on Monday – something the Speaker, John Bercow, said he would have to decide whether to allow.
Before Letwin tabled his amendment, Downing Street had appeared tantalisingly close to achieving majority support for the last-minute deal the prime minister secured on Thursday, which outlines a looser economic relationship with the EU.
Ardent Eurosceptics including Mark Francois and Bill Cash had signalled that they would support the deal, despite the objections of the Northern Irish Democratic Unionist party (DUP).
And several Labour MPs, including Melanie Onn and Sarah Champion, who had rejected Theresa May’s withdrawal agreement, signalled that they too were ready to vote with the government.
The DUP’s backing was key to the success of Letwin’s amendment, after the party rejected Johnson’s Brexit deal on Thursday. It was also supported by 10 independent former Conservatives, including David Gauke and Philip Hammond.
In a passionate speech to the Commons, the DUP MP Sammy Wilson said that the agreement would cut off Northern Ireland from the country “to which we belong”.
“We will not give in to this agreement which we believe does damage to our part of the United Kingdom and which will lead to the focus of attention away from London, towards Dublin,” he said.
Tory MPs left the chamber en masse when the SNP MP Joanna Cherry, who was involved in recent legal action aimed at forcing Johnson to comply with the Benn act, rose to speak.
She asked Bercow whether he would be prepared to sign a letter to the EU requesting an extension, if necessary. “Were I instructed by this house, I would do as instructed, and if I were instructed by a court, I would do as directed,” he replied.
Briefing journalists after the government’s defeat, the prime minister’s official spokesman stonewalled questions about how Johnson planned to avoid negotiating a delay.
“We are not going to add anything to the PM’s words in the house,” he said, adding: “Governments comply with the law.”