Theresa May will ask the EU for an extension to the Brexit deadline to “break the logjam” in Parliament.
The PM says she wants to meet Labour leader Jeremy Corbyn to agree a plan on the future relationship with the EU.
But she insisted her withdrawal agreement – which was voted down last week – would remain part of the deal.
Mrs May said she wanted the extension to be “as short as possible” – before 22 May so the UK does not have to take part in European elections.
The UK has until 12 April to propose a plan – which must be accepted by the EU – or it will leave without a deal.
The UK was supposed to leave the EU on 29 March, but Mrs May agreed a short extension with the bloc after realising Parliament would not agree a deal by the deadline.
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MPs have twice held indicative votes in the Commons to try to find a consensus, but none of the proposals won a majority.
In a statement from Downing Street, Mrs May said she wanted to agree a new plan with Mr Corbyn and put it to a vote in the Commons before 10 April – when the EU will hold an emergency summit on Brexit.
If they do not agree a single way forward, she proposed putting a number of options to MPs “to determine which course to pursue”.
The PM said: “This is a difficult time for everyone. Passions are running high on all sides of the argument, but we can and must find the compromises that will deliver what the British people voted for.
“This is a decisive moment in the story of these islands and it requires national unity to deliver the national interest.”
After the statement, president of the European Council, Donald Tusk, called for patience.