The UK Parliament will be offered the chance to vote for a 'no-deal' Brexit if it refuses to support the withdrawal agreement.
Speaking in the House of Commons, UK Prime Minister Theresa May said MPs will be offered a "meaningful vote" on the deal on March 12th, "at the latest."
She said that if that fails, the House will be asked if it supports leaving the EU without a deal will be held on March 13th.
Should that be rejected, MPs will offered a March 14th vote on a "short, limited" extension to the Brexit process.
"Today I want to reassure the House by giving three further commitments," she said.
"First, we will hold a second meaningful vote by Tuesday the 12th of March at the latest.
"Second, if the Government has not won a meaningful vote by Tuesday the 12th of March, then it will table a motion, to be voted on by Wednesday the 13th of March at the latest, asking this House if it supports leaving the EU without a withdrawal agreement.
She said if that is rejected, the Government will on March 14th "bring forward a motion on whether Parliament wants to seek a short, limited extension to Article 50."
If that is accepted, she will seek to agree that extension with the EU.
It comes as the UK Labour Party called for the British people to be offered a "basic choice" between a deal that can command the support of the House of Commons and remaining in the EU.
The party officially announced its support for a people's vote on Brexit yesterday evening - warning that it aimed to prevent a "damaging Tory Brexit being forced on the country."
Mrs May's announcement came after three of her top ministers publicly indicated they could support a cross-party amendment empowering Parliament to block the UK from leaving without a deal.
There were also reports that as many as 15 other ministers could be prepared to resign if a no-deal scenario is on the cards.
— UK Prime Minister (@10DowningStreet) February 26, 2019
On BBC Radio this morning, Mrs May's de-facto deputy David Lidington repeatedly refused to rule out no-deal.
He warned that extending the process could simply defer the need to face up to difficult decisions - but admitted that a no deal exit would "impose considerable costs to the British economy."
"These negotiations are at an absolutely critical time," he said.
"We need to hold our nerve as a Government; get behind the prime minister; see those decisions and those changes through - and then we have got a very clear pledge."
"A the very latest - I hope it is sooner - but at the very latest by the 12th of March, this will come back to the House of Commons for a clear decision."
This morning, the party's Brexit spokesperson Keir Starmer said it would deliver its "alternative plan" on Brexit to the House of Commons tomorrow.
He said the plan includes a permanent customs union with the EU.
Should that be rejected, the party will back a second referendum to "to prevent a Brexit on the prime minister's red lines."
He told Sky News that: "The basic choice needs to be between a credible Leave option and Remain."
"So that means if the prime minister gets a deal through, that should be subject to the lock of a public vote."
He said a Referendum should not include a 'no-deal' option.
"We've said for a long time no deal would be disastrous for the country," he said. "Pretty well every business says that."
Labour's shift to support a second EU referendum has been heavily criticised by the party's Brexit-supporting MPs.
Bassetlaw MP John Mann said the decision reneges on the party's election manifesto to respect the result of the Referendum and warned that supporting a second vote will be "catastrophic to Labour in the Midlands and the north."