"There's no way to know if an accord will finally be agreed", he said.
More than two years after the United Kingdom voted to leave the European Union in a referendum, May told reporters outside her Downing Street residence that she had won over her divided cabinet, which includes some senior Brexiteers.
"The Brexit talks are about acting in the national interest and that means making what I believe are the right choices, not the easy choices", she said. Some critics have been heartened to see the PM ditch the "Chequers" proposals for a common EU-UK rulebook on trade and now want her to go further.
David Davis (centre) listens to Boris Johnson speaking at a fringe meeting during the Conservative Party Conference.
They say the agreement, which calls for close trade ties between the United Kingdom and the bloc, would leave Britain a vassal state, bound to European Union rules it has no say in making.
Raab said in his resignation letter that "I can not in good conscience support the terms proposed for our deal with the European Union".
Work and Pensions Secretary Esther McVey followed Raab out the door.
"There is no majority in Parliament for her deal", Liberal Democrat leader Vince Cable said.
During the cabinet meeting, British journalists said anger among Brexit-supporting Conservative lawmakers was so high that they might call for a vote of no confidence in her leadership.
Rees-Mogg said May's deal "is not Brexit" because it would keep Britain in a customs union with the EU, potentially for an indefinite period. "I can not support the proposed deal". Brexit secretary Dominic Raab resigned his position on Thursday, Nov. 15, 2018.
Under Conservative rules, a confidence vote in the leader is triggered if 15 per cent of Conservative lawmakers - now 48 - write a letter to the party's 1922 Committee of backbenchers, which oversees leadership votes. A chorus of other Brexiteers have joined Rees-Mogg in calling for a vote of no-confidence.
If Mrs May loses the vote, we enter uncharted territory.
The turmoil is the latest eruption in the Conservative Party's long-running civil war over Europe.
But the beleaguered prime minister appears determined to plow on.
Failure to find support for the Brexit deal risks Sterling falling to 1.2100, the low from March 2017 when the correction from post-Brexit slump started. That could see tariffs on British exports, border che- cks and restrictions on travelers and workers - a toxic mix for businesses.
In a letter to May she wrote that "It will be no good trying to pretend to [voters] that this deal honors the result of the referendum when it is obvious to everyone it doesn't".
Corbyn has said Labour will vote against any deal that does not meet its tests, which include delivering the same benefits Britain now has as a member of the EU customs union and single market.
May said the draft agreement was "the best that could be negotiated".
EU President Donald Tusk on Thursday confirmed the bloc would hold a special summit to seal the hard-fought Brexit agreement with Britain on November 25.
Opposition parties also signalled they would vote against the agreement.
With the United Kingdom - including Northern Ireland - leaving the European Union and assuming World Trade Organisation (WTO) rules, the Republic of Ireland may have little choice but to reimpose a border, conducting checks on goods entering the European Union market to control smuggling.
Opposition parties also signaled that they would vote against the agreement if it comes before them - most likely in December. A no-deal Brexit has no chance of getting agreement.
He claimed: "Both sides would accept the outcome is final for a generation".
If her plan is rejected, there would be a small window of opportunity to put forward an alternative Brexit plan.
"I hope that there will not be too many comments", said Tusk pointedly.