Protesters filled London's streets and packed Parliament Square on Saturday to demand a second referendum vote on Brexit.
The original deadline for Britain to leave the European Union was March 29, but Prime Minister Theresa May secured a little more time from EU leaders to find a deal that both parties agree on.
May has until the end of next week to get a deal through Britain's Parliament. If she is able to get a deal approved by Parliament in that time, the U.K. will have until May 22 to fully exit the EU. But if Parliament doesn't approve a deal by the end of next week, the deadline is April 12. At that time the U.K. would have to create a new plan or leave the EU with a "no-deal" Brexit.
A "no-deal" Brexit would result in the U.K. crashing out of the EU, which is "effectively the world's second-largest economy," as NPR's Frank Langfitt reports.
Concern over a "no-deal" Brexit had loomed over the U.K. leading up to the extension, as Parliament had twice rejected the prime minister's proposals in stunning defeats; the latest was 242 votes for, 391 votes against.
Organizers estimated that 1 million people turned out for the Put It to the People March, but that has not been confirmed independently. A BBC correspondent called it a "very significant march, well into the hundreds of thousands."
Among those who spoke at the march were London Mayor Sadiq Khan, deputy Labour leader Tom Watson and Scotland's First Minister Nicola Sturgeon.
While addressing the crowds at Parliament Square, The Guardian reported, Sturgeon said a longer extension will need to be secured in order to allow time for a second referendum to be held.
"The prime minister and her government have proved completely incapable of delivering on the result of the 2016 vote, which is why it is right that this should now go back to the people," Sturgeon said on stage, according to the paper.
Watson, the Labour Party's deputy leader, also spoke in support of another referendum, saying it would bring the country back together.
"The way to break the stalemate is for Parliament and the people to come together," he said. "The way to reunite our country is to decide on our future together."
Watson continued with a message for May, emphasizing his view that a vote is necessary, saying, "Prime Minister: You've lost control of this process. You're plunging this country into chaos. Let the people take control."
Though Saturday's march was in support of creating a second referendum, another option, to revoke Article 50, has gained enough support this week to crash the U.K. government's petition website. Article 50 is the exit clause in the EU treaty.
In the petition, its creator, Margaret Anne Georgiadou, proposes that instead of trying to find a compromise within Parliament and then the EU, the Brexit efforts should be abandoned all together.
"The government repeatedly claims exiting the EU is 'the will of the people'. We need to put a stop to this claim by proving the strength of public support now, for remaining in the EU. A People's Vote may not happen - so vote now."
The petition was posted Wednesday, and as of Saturday, 4.7 million people had signed their names, pushing it well above the 100,000 signatures required to open a debate in Parliament.
Georgiadou told the BBC that since the petition has gained so much support and attention, she has received three death threats and her Facebook account was hacked.
She also said she wasn't hoping for Parliament to respond to her petition, but she created it "to prove it is no longer the will of the people," she told the news organization. "It was three years ago but the government has become infamous for changing their mind — so why can't the people?"
But not everyone is convinced that those who voted in the original referendum have changed their minds.
A week prior to Saturday's People's Vote march, a pro-Brexit group began a projected two-week march of their own from Sunderland to London. According to the BBC, former U.K. Independence Party leader Nigel Farage rejoined the group Saturday.
The BBC reports that Farage spoke to a group of about 200 pro-Brexit supporters and "said those gathering for the People's Vote march in London were not the majority."