May said Britain faces "stark" choices "and the timetable is clear".
European leaders agreed with Britain on Thursday to delay Brexit by up to six months, saving the continent from what could have been a chaotic no-deal departure at the end of the week.
The one holdout was French President Emmanuel Macron.
It may well be a longer extension than the one the British prime minister asked for, but we will shape this extension in such a way that whenever Britain has approved the withdrawal agreement, Britain can then complete its orderly withdrawal very shortly after.
Earlier on Wednesday, Macron had tweeted: "What is essential: nothing to compromise the European project". She has tried four times before and each time it has been rejected. In contrast to some testy recent summits, there were signs of warmth and even humor.
German Chancellor Angela Merkel arrives at an extraordinary European Union leaders summit to discuss Brexit, in Brussels, Belgium April 10, 2019. An official in the French president's office said the British leader hadn't offered "sufficient guarantees" to justify a long extension. "A no-deal situation is a real option".
The aide said: "Not everything is preferable to a no-deal".
If EU leaders reject the Brexit delay proposal or don't go with Tusk's proposition for a long Brexit delay, Britain will leave the bloc without a deal at 11pm local time on Friday, 12 April.
Earlier, over a working lunch, Mrs May and Mrs Merkel had agreed on the importance of an "orderly withdrawal" from the EU, Downing Street said.
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A blizzard warning is in effect for much of South Dakota and portions of northwestern Nebraska and southwestern Minnesota . Temperatures are mild Tuesday morning, but a cold front arriving later in the day should make conditions colder.
Investors expect heightened political uncertainty after the May 26 election, in which 705 members of the European Parliament MEPs will be elected, or 751 if Britain fails to leave the EU as planned.
This is when the United Kingdom is scheduled to leave the European Union after MPs repeatedly rejected the Prime Minister's deal.
Many Tories are furious at the prospect of participating in European elections given that the country voted to leave the EU almost three years ago. "I will now meet PM @theresa_may for the United Kingdom government's agreement".
"I take responsibility for this position, I think it's for the collective good". "What's still open is how long that extension will be and what the conditions will be".
France argued that a long delay risked serious damage to the European Union, an outcome Paris said was worse than no-deal.
Despite the new agreement, May's future is uncertain. May's leadership. While she survived a vote of non-confidence among Tory MPs last December, a group of Tories is trying to stage another vote.
Every British initiative to get a deal so far has floundered.
Conversations between May's government and the opposition Labour Party are presently not close to breaking the Brexit deadlock, according to John McDonnell, a Labour Party politician. The two sides said they would resume their discussions Thursday. If you try and hold us in against out will, we will make life hard for you.
"It doesn't want to leave without a deal; at the moment it doesn't want to vote for the deal".