- Video report by ITV News Political Correspondent Romilly Weeks
Cabinet ministers have been locked in a meeting for more than four hours as they try to decide whether to support the UK's draft Brexit agreement with the EU.
They met after Theresa May urged MPs to back an agreement which she said would bring the UK "significantly closer" to delivering the result of the 2016 referendum.
The draft agreement of more than 400 pages is understood to involve the UK remaining in a customs union and committing to a "level playing field" on EU rules in areas such as environmental and workplace protections during a backstop period after Brexit.
Cabinet ministers are also looking at a brief political declaration - possibly as short as five pages - setting out an outline framework agreed by EU and UK negotiators for future relations on issues such as trade and security.
This outline remains open for further negotiation ahead of any summit and a final deal will depend on it being acceptable to the UK in its full form.
The Cabinet meeting, scheduled to finish at around 5pm, was thought to be overrunning by up to two hours.
Downing Street said Mrs May will make a statement outside No 10 following the conclusion of the meeting.
Amid feverish speculation about possible Cabinet resignations, a succession of Conservative MPs came out in opposition to the reported contents of the agreement.
Speculation over possible resignations focused on Brexit-backing ministers such as Penny Mordaunt, Andrea Leadsom and Esther McVey.
But sources close to Brexiteer ministers played down the prospect of walkouts, saying "don't expect fireworks today".
The 10 DUP MPs, upon whom Mrs May relies for a majority, appear set to reject a deal if it crosses their red lines.
Speaking in the central lobby of the Palace of Westminster, Arlene Foster said she expected to meet Mrs May later on Wednesday and hoped to be shown the text of the draft agreement in order to clarify its contents.
The DUP leader said there would be "consequences" for Mrs May if she put forward a deal which threatened to break up the United Kingdom, as her party had said in a letter to the PM on November 1.
"If she decides to go against that, if she decides to go against herself - because on many, many occasions she stood up in this very place and said she will not break up the United Kingdom, there will be no difference between Northern Ireland and the rest of the UK - if she decides to go against all that, then there will be consequences," said Mrs Foster.
Speaking earlier at Prime Minister's Questions, Mrs May said: "We will take back control of our borders, our laws and our money. Leave the Common Fisheries Policy and the Common Agricultural Policy while protecting jobs, security and the integrity of our United Kingdom."
But opposition leader Jeremy Corbyn dismissed the deal as a "failure in its own terms”.
He said: "It doesn't deliver a Brexit for the whole country... it breaches the prime minister's own red lines, it doesn't deliver a strong economic deal that supports jobs and industry, and we know they haven't prepared seriously for no deal.
"Under the prime minister's deal we're going spend years with less say over our laws or how our money is spent."
Mrs May said Mr Corbyn was "wrong" in his description and accused Labour of seeking to "frustrate" Brexit.
Earlier, ministers were briefed one by one on the contents of a draft divorce deal reached by officials from the UK and EU after months of protracted talks.
One of the issues holding up the EU and UK reaching a draft Brexit deal was the issue of the Northern Ireland backstop, but an agreement has now been reached on this, resulting in the draft deal.
ITV News Political Editor Robert Peston described the backstop as the "swimming pool" approach, meaning it has a "shallow end and a deep end", when it comes to measures aimed at making sure trade is completely frictionless between Northern Ireland and the Republic of Ireland, and "fairly frictionless" between Great Britain and the other EU 27 states.
"Great Britain would be in the shallow end, Northern Ireland in the deep end", he explained.
The announcement that a draft text had been agreed by officials was met with open hostility from Tory Brexiteers, the Democratic Unionist Party who Mrs May relies on to prop up her Government in key votes, and scepticism from Remain supporters.
Former Brexit secretary David Davis said the UK had reached a “moment of truth” and urged his former colleagues to reject the proposals.
“Cabinet and all Conservative MPs should stand up, be counted and say no to this capitulation,” he said.
While former foreign secretary Boris Johnson urged his ex-Cabinet colleagues to “chuck it out”, telling ITV News the new plan was "vassal state stuff" that would keep the UK "in economic and political captivity".
Jacob Rees-Mogg, chairman of the influential European Research Group of dozens of Tory MPs, added that the proposed deal "looks like an abject surrender to me" and warned it would "divide Northern Ireland from the rest of the United Kingdom and the Prime Minister promised specifically not to do that".
He added that there was also the "issue of the £39 billion" and he wanted to know what the UK would get in return for the large sum of money.
Later on Tuesday, Mr Rees-Mogg he said he had not called for a no confidence vote in Mrs May “but there comes a point at which the policy and the individual become so intimately connected that it will be very hard to carry on supporting this policy”.
Asked if he would be writing a letter to the Tory backbench 1922 Committee about Mrs May’s position, he said: “Not in the next 24 hours.”
Ex-Tory leader Iain Duncan Smith suggested Mrs May’s administration could collapse over the deal.
“If the Cabinet agrees it, the party certainly won’t,” he said, and when asked if the Government’s days were numbered, added: “If this is the case almost certainly, yes.”
Jo Johnson, brother of Boris and a Remain-supporter who quit as transport minister over the Government’s approach, suggested that Cabinet ministers were questioning whether they could support the deal.
Asked if there could be further resignations, he told a rally in support of a second referendum: “I talk to many MPs, colleagues in the Cabinet and elsewhere … I know how much they all think deeply about these issues and they are all looking deep into their consciences and thinking whether they can support this deal.”
The special Cabinet meeting on Wednesday could potentially be a flashpoint for tensions between Brexiteers and Remainers around the table, with speculation that Leave-supporting ministers including Penny Mordaunt, Esther McVey and Andrea Leadsom could be prepared to quit if a deal ties the UK too closely to Brussels.
But sources close to Brexiteer ministers played down the prospect of walkouts, with Mrs Leadsom said to have enjoyed a “good discussion” with the Prime Minister.
Chief Whip Julian Smith told reporters: “I am confident that we will get this through Parliament and that we can deliver on what the Prime Minister committed to on delivering Brexit.”
But the challenge of getting a deal through Parliament appears even more difficult for Mrs May than winning the support of her Cabinet.
Scotland’s First Minister Nicola Sturgeon said MPs must not fall for Downing Street “spin” that rejecting the deal means crashing out of the EU and “instead we should take the opportunity to get better options back on the table”.
The deal follows intense negotiation in Brussels, with measures to prevent a hard border on the island of Ireland the main stumbling block.
There will also be a review in July 2019 six months before the end of the transition period, at which it will be determined how to proceed – a new trade deal, the backstop or an extension to the transition period.
The Daily Telegraph revealed that Attorney General Geoffrey Cox told Cabinet that Northern Ireland will be in a “different regulatory regime” under the customs backstop and subject to EU law and institutions, something that may “cross a line” for the DUP.
Labour leader Jeremy Corbyn said the party would vote against the deal if it failed to meet its tests.
“From what we know of the shambolic handling of these negotiations, this is unlikely to be a good deal for the country,” he said.
But his own approach to Brexit will come under attack from former prime minister Tony Blair on Wednesday.
In a speech in London Mr Blair will lash out at the “abject refusal of the Labour leadership to lead the country out of the Brexit nightmare”.