British lawmakers debated whether to accept the Brexit deal that Prime Minister Boris Johnson struck with the European Union during their first Saturday session in 37 years.

Johnson appealed to lawmakers to back his last-minute deal after his plans were plunged into chaos by his opponents’ moves to derail the legislation.

The vote comes more than three years since the United Kingdom voted 52 percent to 48 percent to leave the EU, Reuters reported.

House of Commons speaker John Bercow opened the session saying he would first allow a vote on an amendment that puts the decision on Johnson’s deal off until another day, according to reports. It would make support for the deal conditional on the legislation to implement it being passed by Parliament, something that could take several days or weeks.

If the bid to put off the decision passes, Johnson would have to ask the EU for another delay. Last month, Parliament passed a law requiring Johnson to ask the EU for a Brexit delay until Jan. 31, unless he has secured approval for his deal by the end of Saturday.

That move was intended to prevent a “hard Brexit,” or departure from the EU with no deal, on Oct. 31. Johnson has promised a hard Brexit if Parliament doesn’t pass his plan, but economists say a no-deal breakup would plunge the UK’s economy into recession.

Johnson said he would ask for the extension if necessary, but “it cannot change my judgment that further delay is pointless, expensive and deeply corrosive of public trust.”

As Parliament debated, tens of thousands of people gathered to demand a new referendum. The protesters, from around the United Kingdom, waved EU flags and carried signs calling for Brexit to be halted ahead of a planned march through the city.

“I am incensed that we are not being listened to,” said Hannah Barton, 56, a cider maker from central England, who was draped in an EU flag. “Nearly all the polls show that now people want to remain in the EU. We feel that we are voiceless.

“This is a national disaster waiting to happen and it is going to destroy the economy.”

James McGrory, director of the People’s Vote campaign, which organized the march, said ahead of the protest that the government should heed the anger of pro-Europeans and hold another referendum on EU membership.

“This new deal bears no resemblance to what people were promised and so it is only right that the public deserve another chance to have their say,” he said.