London (CNN) - UK Prime Minister Boris Johnson has been forced to ask the European Union for an extension to the Brexit process, an outcome he once notoriously described as worse than being "dead in a ditch."
But in an extraordinary development, he simultaneously disowned the request, declaring that the three-month delay would be "corrosive."
Johnson was compelled by law to demand the delay after lawmakers withheld approval of his Brexit deal. In a day of intense political drama in London, MPs voted to postpone ratification of the deal until Parliament has passed the complex set of legislation required to enact it.
Downing Street demonstrated Johnson's disdain for the process by sending an unsigned photocopy of the legally mandated letter by email to the EU Council President, Donald Tusk. It was accompanied by a covering letter from a senior civil servant explaining that the letter was being sent in order to comply with a law passed by Parliament last month which is designed to prevent a no-deal Brexit.
A third letter was sent to EU leaders, in which Johnson explained why the delay was a bad idea. It would be "deeply corrosive," he wrote int letter, according to a UK government source.
Tusk said he had received the correspondence and would consult with other EU leaders on next steps.
Boris Johnson requested a Brexit extension from EU leaders, and also asked them to turn it down
"I will not negotiate a delay with the EU, and neither does the law compel me to do so," Johnson had told lawmakers earlier. "Further delay will be bad for this country."
The Labour leader, Jeremy Corbyn, blasted Johnson from across the floor of the House of Commons. "The Prime Minister must now comply with the law," he said. "He can no longer use the threat of a no-deal crash-out to blackmail MPs to support his sellout deal."
Moment of victory denied
Government aides were furious at the result of the vote in Parliament, as it denied Johnson the chance to declare a Brexit victory on Saturday. After two days of arm-twisting since Johnson returned with a new deal from Brussels on Thursday, Downing Street believed it had secured the numbers required to pass it, albeit by a razor-thin margin.
Johnson's nemesis was former Conservative government minister Oliver Letwin, who proposed the amendment that delayed Parliament's approval. He said it was an "insurance policy" to ensure the UK would not "crash out" of the European Union without a deal on October 31.
Under legislation known as the Benn Act, the UK government was required to request an extension to the Brexit process until January 31, if a deal was was not ratified by the end of Saturday.
Those provisions would have fallen away if Johnson had succeeded in getting his deal through the House of Commons. But Letwin and his allies were concerned that a no-deal Brexit could still happen at the end of October if, by then, lawmakers had failed to pass the complex set of legislation required to enact the departure deal.
Letwin said his amendment was an "insurance policy" designed to avoid an accidental no-deal.
In the end, the Letwin amendment passed by 322 votes to 306. In a twist of political fate, the outcome was decided by the 10 MPs of the Democratic Unionist Party, the Northern Ireland group that nominally props up Johnson's minority government in the House of Commons.
Boris Johnson leaves Downing Street to head for the House of Commons on Saturday.
The DUP was deeply unhappy with terms of Johnson's deal, under which Northern Ireland effectively remains in the EU customs union, putting the province in a different economic arrangement to the rest of the UK. Its MPs were particularly furious that Johnson had cast them aside, traveling to Brussels on Thursday to sign his Brexit deal with EU leaders without securing their support.
"We are cut off from the country to which we belong," said Sammy Wilson, the DUP's Brexit spokesman, in an impassioned speech in the House of Commons.
Prime Minister Boris Johnson failed to persuade lawmakers to back his plans.
Johnson's plea to lawmakers
In the first weekend sitting of Parliament for 37 years, Johnson had implored MPs from all sides of the House of Commons to back his Brexit deal and support a "shared sense of destiny."
He received notable backing from his predecessor, Theresa May, who as Prime Minister had refused to accept many of the provisions related to Northern Ireland now agreed by Johnson. "If you want to deliver Brexit, if you want to keep faith with the British people, if you want the country to move forward, then vote for the deal today," she said.
Theresa May gave enthusiastic backing to her successor, Boris Johnson.
In the end, May's support was not enough. "Alas, the opportunity to have a meaningful vote has effectively been passed up," an angry Johnson told lawmakers after the Letwin amendment was passed. "The meaningful vote has been voided of meaning."
The day dubbed as "Super Saturday" had turned into something of an anti-climax. But Johnson said the government would press on with its plans to put legislation to enact the withdrawal agreement before Parliament next week. "The best thing for the UK and for the whole of Europe is for us to leave with this new deal on October 31," he said.
What happens next?
Johnson's contradictory correspondence to the EU is bound to land him in court. A related case was already due to be heard at Scotland's highest court, the Court of Session in Edinburgh, on Monday, and this will likely be the venue for the first legal challenge.
Opposition lawmakers were furious. John McDonnell, Labour's finance spokesman, said on Twitter: "Johnson is a Prime Minister who is now treating Parliament and the Courts with contempt. His juvenile refusal to even sign the letter confirms what we always suspected that Johnson with his arrogant sense of entitlement considers he is above the law and above accountability."
Meanwhile Jacob Rees-Mogg, the leader of the House of Commons, said the government would bring forward another vote on Johnson's Brexit deal on Monday.
Ordinarily, the same provision can't be voted on twice in a parliamentary session. That convention scuppered ex-Prime Minister May's plans to hold repeated votes on her withdrawal deal. But it was not clear whether Saturday's proceedings in Parliament counted as a vote on Johnson's deal, because it was amended by the Letwin measure. Speaker of the House John Bercow said he would rule on the matter Monday.
Crowds march through central London on Saturday to demand a People's Vote on the government's new Brexit deal.
While lawmakers were debating and voting in Parliament, up to 1 million protesters marched through central London to call for a second Brexit referendum, according to protest organizers.
In a statement, the People's Vote march estimated the amount of attendees by the number of coaches bringing people to the demonstrations, leaflets distributed publicizing the march and online sign-ups to the event which have exceeded previous events. Authorities have not given estimates of crowd sizes.
CNN's Luke McGee contributed to this report from London.