British Prime Minister Theresa May has postponed a crucial parliamentary vote on her Brexit deal because she said it "would be rejected by a significant margin".
She said MPs backed much of the deal she has struck with the EU but there was concern over the Northern Ireland backstop plan.
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Mrs May said she believed she could still get the deal through if she addressed MPs' concerns and that what she intended to do in the next few days.
However, Speaker John Bercow - who chairs debates in the House of Commons - called on the government to give MPs a vote on whether Tuesday's vote should be cancelled, saying it was the "right and obvious" thing to do given how angry some MPs were about the cancellation.
Labour leader Jeremy Corbyn said the government was in "complete chaos" and urged Mrs May to stand down.
The pound fell sharply in response to the reports earlier of a likely delay.
The deputy leader of the DUP - the Northern Ireland party whose backing Theresa May needs to win key votes - Nigel Dodds, said the situation was "quite frankly a bit of a shambles" and the PM was paying the price for crossing her "red lines" when it came to Northern Ireland.
Scottish nationalists pledged to support a vote to bring the government down.
Northern Ireland backstop
In her statement Mrs May said she would be "deferring" the Commons vote until she had made efforts to address concerns over the Northern Ireland border backstop plan.
She told MPs she would be speaking to EU leaders ahead of a summit later this week, about the "clear concerns" expressed by MPs.
And she would also be "looking closely at new ways of empowering the House of Commons to ensure that any provision for a backstop has democratic legitimacy".
She wants to enable MPs to place obligations on the government "to ensure that the backstop cannot be in place indefinitely".
But DUP leader Arlene Foster said she had told the prime minister in a phone call that the "backstop must go".
She again rejected all other alternatives that have been proposed to her deal - including a further referendum and leaving without a deal
EU court decision
Theresa May's deal has been agreed with the EU - but it needs to be backed by the UK Parliament if it is to become law ahead of the UK's departure.
Mrs May has also been speaking to EU leaders about re-opening the withdrawal agreement, something both sides have previously ruled out.
The decision to halt the vote came just hours after as the European Court of Justice - the EU's top court - ruled the UK could cancel Brexit without the permission of the other 27 EU members.
But European Commission spokeswoman Mina Andreeva said the EU would not renegotiate the Withdrawal Agreement.
I’ve heard the PM is trying to get more legal oomph behind the language in the Withdrawal Agreement of using “best endeavours” to reach a trade deal which removes the need for the backstop ie solve the problem in this para of last week’s legal advice. (As usual, let’s see) pic.twitter.com/6FzH849yXl— Adam Fleming (@adamfleming) December 10, 2018
Tory rebels planned to vote against deal
Dozens of Conservative MPs had been planning to join forces with Labour, the SNP, the Lib Dems, Plaid Cymru and the DUP to vote down Mrs May's deal.
The Tory rebels and the DUP do not like the Northern Ireland "backstop", a legally-binding proposal for a customs arrangement with the EU, which would come into force if the two sides' cannot agree a future relationship which avoids the return of a visible Northern Ireland border.
Labour leader Jeremy Corbyn, who was hoping to use a defeat for Mrs May on Tuesday to force a general election, said the prime minister should have "have gone back to Brussels to renegotiate or called an election" when it became clear she would not get her deal through Parliament. "We don't have a functioning government," he added.