The UK Prime Minister has insisted the draft Brexit Withdrawal Agreement accepted by her Cabinet offers the best possible deal in the circumstances.
It comes as five Conservative MPs resign their positions in protest at the proposals.
Pitching the deal to her colleagues in the House of Commons, Theresa May said a failure to accept it would plunge the country “back to square one."
She said the EU would not accept any deal that did not include a backstop preventing a return to a hard border in Ireland - and noted that both sides have said they never want to have to use it.
“While some people might pretend otherwise, there is no deal which delivers the Brexit the British people voted for which does not involve this insurance policy,” she said.
“Not Canada++, not Norway for now, not our own whitepaper.
“The EU will not negotiate any future partnership without it.”
Met with reps from Northern Ireland parties earlier to discuss the latest developments in the #Brexit negotiations. The draft Withdrawal agreement includes important assurances re the Good Friday Agreement & the need for continued close relations among all parts of these islands. pic.twitter.com/VNRZxKaUAK
— Leo Varadkar (@campaignforleo) November 15, 2018
She lashed out at politicians who had suggested she should “simply rip up” the UKs commitment to a backstop - made in writing in December and March.
“This would have been an entirely irresponsible course of action,” she said.
“It would have meant reneging on a promise, made to the people of Northern Ireland during the referendum campaign and afterwards, that under no circumstances would Brexit lead to a return to the borders of the past.
“And it would have made it impossible to deliver a Withdrawal Agreement
“As Prime Minister of the UK I have a responsibility to people in every part of our country and I intend to honour that promise.”
She said the EU had made a number of concessions in the talks and noted that if there is no trade deal by the end of 2020, “the UK will be able to make a choice between the UK-wide temporary customs arrangement or a short extension of the implementation period.”
She said the deal is “explicit that it is temporary, that the Article 50 legal base cannot provide for a permanent relationship and there is also a mechanism by which the backstop can be terminated.”
"Choice is clear"
She said the statement on the future relationship between the two blocs offers a relationship that “no other major advanced economy” enjoys with the EU - and noted that the draft agreement was a “decisive breakthrough” in the process.
“Once the final deal is agreed, I will bring it to Parliament and I will ask MPs to consider the national interest and give it their backing,” she said.
“Voting against the deal would take us all back to square one.
“It would mean more uncertainty, more division and a failure to deliver on the decision of the British people that we should leave the EU.”
She told the House of Commons that the “choice is clear” for MPs.
“We can choose to leave with no deal; we can risk no Brexit at all or we can choose to unite and support the best deal that can be negotiated,” she said.
Mrs May made her pitch after three ministers resigned in protest at the proposals.
"Long road ahead"
The Taoiseach Leo Varadkar and EU leaders have welcomed the 585 page document - but Theresa May faces a huge fight to get it signed off on by politicians.
Speaking this morning, chief EU negotiator Michel Barnier warned that "our work is not finished" adding that there is still a "long road ahead" for all sides.
Mr Varadkar said the deal offers a “satisfactory outcome” on Irish priorities – including protecting the Good Friday Agreement and the Common Travel Area.
The draft agreement includes a single backstop preventing a return to a hard border in Ireland.
It will have the form of a temporary customs union between the UK and the EU that will remain in place unless and until a new trade deal is agreed to avoid the need for border checks.
It includes specific provisions for Northern Ireland that will see it aligned more deeply with EU customs and regulations than the rest of the UK.
The provisions relate to agriculture, the environment, state aid and other areas.
There will also be checks on goods traded from Northern Ireland to the rest of the UK.
The document states that the EU and the UK will use their "best endeavours" to come to a future trade agreement to avoid the backstop, and notes the transition period can also be extended.
It is understood the backstop includes an agreed review mechanism – however, the UK will not be permitted to unilaterally walk away from the deal.
Any exit would have to be agreed by a joint commission made up of top decision makers from the EU and UK.