May made a blunt appeal to skeptical lawmakers on Monday to back her divorce deal with the EU: It isn't flawless, but it's all there is, and the alternative is a leap into the unknown.
Under the terms of the agreement, the whole of the United Kingdom will remain in a customs union with the EU "unless and until" the bloc agrees there is no prospect of a return to a hard border.
The last big obstacle to a deal was overcome on Saturday, when Spain lifted its objections over the disputed British territory of Gibraltar.
"This deal delivers for farmers in Wales, who deserve better than the Common Agricultural Policy".
Brexiteers want negotiators to return to Brussels to amend the deal, but European leaders have said that they have little room to improve it and that there is nothing more to talk about. Her limits as vote-wrangler will be tested in her own Parliament, where pro-Brexit lawmakers have hammered the plan as failing to break decisively enough from Brussels and pro-E.U. forces have condemned it as a self-inflicted wound that hurts British voters.
MP Jacob Rees-Mogg, who is leading Conservative rebels against the deal, told Yahoo Finance UK that it "rather undermines the prime minister's claim that no other deal is possible".
The deal consists of a legally binding withdrawal agreement that runs more than 580 pages, and a 26-page political declaration on future relations.
If British legislators back the plan devised by May's government, then an EU Withdrawal Agreement bill will be introduced in parliament, which must be ratified by the members before it can proceed to a European Parliament vote.
"This is the maximum we can all do", he said.
The agreement calls for Britain to stay in the bloc's customs union and largely in the EU single market, without the power to influence the rules, regulations and laws it will be obliged to obey for a 21-month-long transition period following formal withdrawal on March 29.
The comments came as it was confirmed that MPs will vote on Mrs May's Brexit deal on December 11 after five days of debate.
Theresa May has urged MPs to embrace a "brighter future" and back her Brexit plan as European Union leaders finally signed off on the deal hammered out in Brussels.
It added continued uncertainty means business investment and economic activity is likely to continue to be lower.
"Theresa May wants to blackmail us into voting for her bad deal by thinking the only alternative is the disaster of crashing out with no deal", Joanna Cherry, a Scottish National Party lawmaker and one of the group of Scottish politicians who instigated the case told Reuters.
However, it said this would rise to 3.5%-8.7% if there was a no deal Brexit.
Opposition Labour Party chief Jeremy Corbyn says his party will "reject the deal".
"This will never get through.it is as dead as a dodo", Conservative lawmaker Mark Francois said, adding he agreed with the Sun newspaper's verdict that the deal was "a surrender".
As for what the deal entails, it does allow for an orderly Brexit, but in doing so just preserves the status quo for nearly two more years.
"I recognise some European leaders are sad at this moment, but also some people back at home in the United Kingdom will be sad at this moment".