Boris Johnson has threatened to pull his Brexit deal and force a general election if MPs delay the departure date for leaving the EU until January.

In a dramatic intervention in the Commons, the prime minister said defeat on his bid to ram the legislation through in just three days – the so-called programme motion – could see it scrapped altogether.

“If parliament refuses to allow Brexit to happen, and instead gets its way and decides to delay everything until January or possibly longer, in no circumstances can the government can continue with this,” he told MPs

“I must say the bill will have to be pulled and we will have to go forward to a general election.”

The threat raises the stakes enormously for the vote on the controversial fast-track timetable – which will follow if, as expected, MPs give backing in principle to the bill.

Unless the withdrawal agreement bill clears the Commons by Thursday, the prime minister will suffer the embarrassment of having to abandon his pledge of leaving the EU by 31 October.

In the only previous example of a programme motion defeat, on House of Lords reform, the Cameron government pulled the legislation rather than press on with no guillotine on debate.

However, Mr Johnson suggested he would do the same only if defeat was coupled with the EU agreeing a three-month delay – when a shorter extension, to allow ratification, is also possible.

It also remains unclear whether the prime minister could force an election if he tried, after Labour and other opposition parties blocked it last month.

Supreme Court verdict: Boris Johnson prorogation unlawful Show all 16 1 /16 Supreme Court verdict: Boris Johnson prorogation unlawful Supreme Court verdict: Boris Johnson prorogation unlawful The Supreme Court has ruled against Boris Johnson by declaring his government unlawfully shut down parliament for five weeks EPA Supreme Court verdict: Boris Johnson prorogation unlawful Lady Hale handed down the historic verdict, hailed by opposition MPs and anti-Brexit campaigners. She said all 11 judges were unanimous in deciding that the case is “justiciable”, so the government loses that part of the argument. “The court is bound to conclude therefore that the decision to advise Her Majesty to prorogue was unlawful because it had the effect of frustrating or preventing the ability of Parliament to carry out its constitutional functions.” EPA/Supreme Court Supreme Court verdict: Boris Johnson prorogation unlawful Gina Miller and her team react outside the Supreme Court are the verdict. She said: “Today is not a win for any individual or cause. It is a win for Parliamentary sovereignty, the separation of powers and independence of our British courts. Crucially, today’s ruling confirms that we are a nation governed by the rule of law, laws that everyone, even the Prime Minister, are subject to." PA Supreme Court verdict: Boris Johnson prorogation unlawful A person dressed as a caricature of British Prime Minister Boris Johnson in a prison uniform stands outside the Supreme Court AP Supreme Court verdict: Boris Johnson prorogation unlawful Labour leader Jeremy Corbyn called for Mr Johnson to “consider his position” following the landmark decision, while Lib Dem leader Jo Swinson said he was “not fit to be prime minister” Getty Supreme Court verdict: Boris Johnson prorogation unlawful Scottish National Party (SNP) Westminster leader Ian Blackford raises his arms as he comes outside. He said: "This is an absolutely stunning judgement by the Supreme Court today." He went on to say, "we all want to get back to work, and quite frankly, on the back of this, Boris Johnson must resign immediately." AFP/Getty Supreme Court verdict: Boris Johnson prorogation unlawful Crowds outside celebrated the verdict AP Supreme Court verdict: Boris Johnson prorogation unlawful Delegates at the Labour party conference applaud after hearing the news AFP/Getty Supreme Court verdict: Boris Johnson prorogation unlawful Speaker John Bercow said MPs must now “convene without delay” and confirmed the Commons would return at 11.30am on Wednesday AFP/Getty Supreme Court verdict: Boris Johnson prorogation unlawful Gina Miller said: "“As a result of this judgment, Parliament is open, it was never prorogued. I urge MPs to get back to work immediately.” AP Supreme Court verdict: Boris Johnson prorogation unlawful MPs Anna Soubry, Liz Saville Roberts and Caroline Lucas, together with SNP leader Ian Blackford, react. Green MP Caroline Lucas has said the Supreme Court’s decision is “just the start” Reuters Supreme Court verdict: Boris Johnson prorogation unlawful “The UK deserves a Prime Minister and a Government who act with honesty, integrity and in a manner consistent with our constitution, at all times." AFP/Getty Supreme Court verdict: Boris Johnson prorogation unlawful Anti-Brexit supporters react as they gather outside the Supreme Court in London, Tuesday, Sept. 24, 2019 as it makes it's decision on the legality of Prime Minister Boris Johnson's five-week suspension of Parliament. (AP Photo/Frank Augstein) Frank Augstein AP Supreme Court verdict: Boris Johnson prorogation unlawful The SNP’s Joanna Cherry QC says: “Boris Johnson’s position is untenable and he should have the guts to resign.” PA Supreme Court verdict: Boris Johnson prorogation unlawful epa07865617 Protesters react outside the Supreme Court after the result of a hearing on the prorogation of parliament, in London, Britain, 19 September 2019. The Supreme Court ruled that the suspension of parliament by British Prime Minister Boris Johnson was not lawful. EPA/NEIL HALL NEIL HALL EPA Supreme Court verdict: Boris Johnson prorogation unlawful Tom Tugendhat MP returned to the chamber in the House of Commons within minutes of the Supreme Court ruling PA

Opening debate on the legislation, Mr Johnson said: “If we delay again I am afraid that we will miss an opportunity to heal the divisions between us and the paralysis will continue.”

And he added: “I will argue at the election ‘let's get Brexit done’ and the leader of the opposition will make his case to spend 2020 having two referendums: one on Brexit, and one on Scotland and the people will decide.

“There is another path and that is to accept as I have done that this deal does not give us everything we wanted.”

But the Liberal Democrats accused the prime minister of “childish blackmail” in a bid to “rush through this bad Brexit deal without proper scrutiny”.

There is a clear motive for No 10 to issue dark threats about an election – to strongarm both Tory MPs determined to deliver Brexit and Labour MPs who fear going to the polls under Jeremy Corbyn.

Previous anonymous warnings from Downing Street sources – notably that Mr Johnson would not request a Brexit delay last weekend, which he then did – have proved false.