A draft deal, which is believed to stretch to more than 500 pages, was signed off by negotiators from both the European Union and U.K. on Tuesday. It will now need the approval of senior lawmakers, and then the whole U.K. Parliament, before it can be put into action.
May began the crucial Cabinet meeting of senior politicians at 2:00 p.m. London time (9:00 a.m. ET) on Wednesday in a bid to persuade her inner circle to back the draft "technical agreement."
Earlier at Prime Minister's Questions, May said that Britain and Northern Ireland was now "significantly closer" to delivering what the U.K. voted for in 2016. The prime minister added that Cabinet would now "decide on the next steps in the national interest."
If May can get her Cabinet's backing, that paves the way for a special summit with the EU dedicated to Brexit at the end of November.
In response the leader of the main opposition party, Jeremy Corbyn, said May had struck a bad deal that would lead to an "indefinite half-way house without any real say" over rules from Brussels.
At the same session, a lawmaker from her own Conservative Party and Brexiteer Peter Bone told May that if her plan gave away too much to Europe, she risked losing the support "of many Conservative MPs (members of Parliament) and millions of voters."