Several of her own MPs denounced the draft political declaration on the future economic partnership as a “surrender” to Brussels, putting Commons approval for the deal in the next three weeks in doubt.
The document sparked a furious row over between the Prime Minister and the SNP, whose Westminster leader claimed fishermen had been “thrown overboard as if they were discarded fish”, and split the Scottish Conservative group at Westminster.
Agreement between negotiators in Brussels paves the way for the UK’s exit deal - a package including the political declaration and the 585-page withdrawal agreement setting out the terms of the ‘divorce’ from the EU - to be approved by European leaders at a special summit on Sunday.
“The draft text that we have agreed with the Commission is a good deal for our country and for our partners in the EU,” told the House of Commons.
“It honours the vote of the British people by taking back control of our borders, our laws and our money while protecting jobs, security and the integrity of our precious United Kingdom.”
As many as 80 Conservative MPs have publicly declared they will not vote for the deal.
A Downing Street charm offensive aimed at convincing eurosceptics that a backstop plan for the Irish border can be avoided using “alternative” customs technologies appeared to have failed, with Iain Duncan Smith telling Mrs May that “none of this is at all workable” unless the withdrawal agreement is renegotiated.
Dominic Raab, the former Brexit Secretary, claimed the backstop “ties the UK to the customs union and single market rules with no voice” and will be used by the EU as “the starting point for future relations to build on”.
Mr Raab said Brexit voters wanted to “take back control” but said it was “the regrettable but inescapable reality that this deal gives even more away”.
And the chief whip of the DUP, Sir Jeffrey Donaldson, also called on the Prime Minister to renegotiate, telling her: “If she wants to have the support of my party for the withdrawal agreement then we need to see an end to the backstop and those alternative arrangements put in place.”
Mrs May told MPs that “the best way to ensure the backstop is not used is to get the future relationship into place” before the end of the post-Brexit transition phase, which is scheduled to end in December 2020, but could be extended as far as the end of 2022 if talks drag on.
The draft political declaration outlines the objectives for trade and security cooperation after Brexit.
European Council president Donald Tusk announced it had been “agreed at negotiators’ level and agreed in principle at political level” and sent to Britain’s 27 European partners for further consideration.
“The Commission President has informed me that it has been agreed at negotiators’ level and agreed in principle at political level, subject to the endorsement of the Leaders,” he added.
An earlier draft of the declaration came to seven pages, but the final version is now 26 pages long.
Unlike the withdrawal agreement, the political declaration is not legally binding, but is linked to the UK’s ‘divorce’ terms.
The UK Government has said that the withdrawal agreement, including the £39bn financial settlement, will not be enacted without the political declaration.
Jeremy Corbyn criticised the trade outline, calling it “26 pages of waffle” and a blueprint for a deal that is the “worst of all worlds”.
“The only certainty contained within these pages is that the transition period will have to be extended or we will end up with a backstop and no exit,” the Labour leader told MPs.
“It represents the worst of all worlds, no say over the rules that will continue to apply and no certainty to the future.”
He added: “We have 26 pages of waffle, this empty document could have been written two years ago.”
Mr Corbyn also called on the PM to “abandon her poisonous rhetoric” on immigration.
Instead of negotiating a “new, comprehensive customs union”, he said the Tories were more interested in “dog whistling on immigration”.
Focusing on fishing, SNP Westminster leader Ian Blackford called the document “an absolute dereliction of the promises Scottish Conservative members and [Environment Secretary Michael Gove] made to Scotland - shame on them.”
He asked if her Scottish MPs and Scottish Secretary David Mundell had agreed to the political declaration, adding: “Is it not the case that she’s just lost further critical votes on the deal because Scottish Tory MPs could not possibly vote in favour of this sell out of Scottish fishing interests?”
The Prime Minister was expected to speak to a number of EU leaders last night. She acknowledged that she must still convince some of them to back the deal, with the Spanish Prime Minister threatening to vote against it because the political declaration does not grant Madrid a veto over the application of future trade agreements in Gibraltar.
Speaking in Downing Street before addressing MPs, the Prime Minister said she had spoken to Prime Minister Pedro Sánchez on Wednesday night and was “confident that on Sunday we will be able to agree a deal that delivers for the whole UK family, including Gibraltar.”
Two-thirds of the 27 other EU members must agree to the deal for it to be approved.
Last night Mrs May met Austria’s chancellor in London ahead of Sunday’s summit.
Ahead of the meeting, Sebastian Kurz said he hoped to get a “realistic picture” of May’s chances of getting the deal through Westminster, and warned: “Reopening the deal is not an option.”