Protesters take part in the Put It To The People March on March 23, 2019, in London.
Dan Kitwood/Getty Images

In photos: Thousands join 'People's Vote' protest

Updated 4:43 PM ET, Sat March 23, 2019

Protesters take part in the Put It To The People March on March 23, 2019, in London.
Dan Kitwood/Getty Images

Large crowds marched in London on Saturday demanding a second Brexit referendum.

In a letter to members of Parliament on Friday, Prime Minister Theresa May said that a third meaningful vote on her Brexit deal may not happen.

"If it appears that there is not sufficient support to bring the deal back next week, or the House rejects it again, we can ask for another extension before 12 April, but that will involve holding European Parliament elections," May wrote.

The Prime Minister must now persuade UK lawmakers to back her deal in Parliament, where she faces an uphill battle -- particularly after alienating many when she blamed them for the Brexit chaos in a speech Wednesday.

The outcome of Brexit may not yet be decided, but it has already done major damage to the UK economy.

The vote to leave the European Union in June 2016 caused the pound to weaken dramatically and ushered in years of uncertainty that has reduced economic activity and triggered a slump in investment.

The economy is now 2% smaller than it would have been had the United Kingdom chosen to remain in the bloc, according to the Bank of England. The economic output lost since the referendum is worth about 800 million pounds ($1 billion) per week, or 4.7 million pounds ($6 million) per hour.

And with UK politics in disarray, there's still a risk the country will leave the European Union without a transitional deal to protect trade, known as a no-deal Brexit.

The fallout from that scenario would be worse than the 2008 financial crisis, according to the Bank of England.