"If the votes go this week in a way which means that the prime minister's policy as she has set out and stuck to rigidly over the course of the last two-and-a-bit a years is taken away, dismantled slowly by Parliament this week, I think it would be very hard for the prime minister to stay in office for very much longer", Morgan told the BBC.
The legal judgement on the instrument issued by Attorney General Geoffrey Cox today noted: "T$3 he legally binding provisions of the joint instrument and the content of the unilateral declaration reduce the risk that the United Kingdom could be indefinitely and involuntarily detained within the protocol's provisions at least in so far as that situation had been brought about by the bad faith or want of best endeavours of the European Union".
A weakened May, her authority shredded by successive Brexit defeats in Parliament, said her Conservative lawmakers could vote Wednesday night according to their conscience, rather than having to follow a party line.
That appeared unlikely after Cox's assessment. The Attorney General will publish his legal opinion before the vote.
In Westminster, the chairman of a research group of pro-Brexit MPs Jacob Rees-Mogg said his group has a team of lawyers reviewing the agreement.
"The instrument has legal force, it complements the withdrawal agreement without reopening it", Juncker said, adding Leo Varadkar, the prime minister of Ireland, would back it.
She warned in a speech Friday that rejecting her deal again would create a "moment of crisis".
German EU affairs minister Michael Roth, called it "a far-reaching compromise".
The Daily Mirror instead described the Prime Minister's trip to Brussels on Monday night as a desperate and "theatrical" bid to convince her MPs to back her "bad deal". Labour Brexit spokesman Keir Starmer expressed skepticism about whether May had won substantive concessions.
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The senator cautioned that Trump's position may still change - "It is only Wednesday , and it is the Trump administration". John Cornyn, R-Texas, an adviser to Senate GOP leadership, said of the eleventh-hour White House lobbying effort.
But talks appeared to be stuck over the final point - a United Kingdom statement which would help the Attorney General change his legal advice on whether the backstop would last forever or not.
May has also spoken to European Commission President Jean-Claude Juncker amid speculation the British leader might dash to meet Juncker and other EU leaders in France.
Britain will slash import tariffs in case of a no-deal Brexit and will not apply customs checks on the border with Ireland, the government said on Wednesday.
Another defeat in parliament could see Britain sever ties with its closest trading partner on March 29 with no new arrangements, causing huge disruption on both sides of the Channel. Brexit supporters in Britain fear the backstop could be used to bind the country to European Union regulations indefinitely.
He said the changes should overcome lawmakers' qualms about a mechanism in the deal created to keep an open border between Britain's Northern Ireland and European Union member Ireland. It is irritated, too, that Britain is seeking changes to an agreement that Ms.
She also said a plan is being prepared for how to deal with the border in Ireland.
"It is not, these doubts and fears can be put to bed", he said.
Lawmakers are expected to try and make changes to the text of the statement to show that there is majority support for an alternative course of action or to make backing the deal conditional on something such as a second referendum.
"I have got to say that if you look at what the prime minister has said so far it seems to fall short of what she, herself, had promised".