Work and Pensions Secretary Esther McVey followed Raab out the door.
The resignation came the day after the prime minister revealed her soft Brexit Chequers plan at her country retreat in July.
Ms Trevelyan wrote Thursday morning: "I can not agree to a deal in which my country will have its unique innovative spirit crushed by removing the great opportunity of competitive advantage for decades ahead".
But who knows how many ministers spent the night pacing their lounge rooms deciding whether to quit or stay, and whether any of them will be having an uncomfortable conversation with the prime minister this morning.
With Downing Street extremely nervous of a growing backbench move to topple the PM, frantic efforts have been made by whips and ministerial aides to limit the number of letters calling for a vote of confidence in her.
This is a developing story.
He asked to rewrite the draft withdrawal agreement and a delay to the European Union council meeting scheduled for November 25, which was supposed to sign off the plan.
Australia is now negotiating a free trade deal with the European Union where it is pressing for cuts to European Union agriculture subsidies.
On the issue of the border in Ireland, May said the withdrawal agreement has set out an insurance policy should a permanent new UK-EU relationship not be ready by the time the implementation period ends at the end of 2019.
But, during a press conference in Downing Street, Mrs May said abandoning the withdrawal deal would be "to take a path of deep and grave uncertainty when the British people just want us to get on with it", she warned.
Also, the British Parliament has to agree to.
No.10 sources stress that while the legal Withdrawal Agreement is unlikely to be changed, the outline "political declaration" that accompanies it is clearly up for further negotiation.
It also needs approval from Britain's Parliament before the United Kingdom leaves the bloc on March 29 - and even if May survives as leader, the chances of that look slim. May's allies in the Democratic Unionist Party and opposition parties.
May insisted the draft deal would protect jobs, trade, security co-operation, the Northern Ireland peace process and an open Irish border.
Jeremy Corbyn, the leader of the main opposition Labour Party, said his party would vote against the proposed agreement.
Ian Blackford, who heads the Scottish National Party in Parliament, said the deal was "dead on arrival" and urged May to "stop the clock and go back to Brussels".
"On both sides, we have exhausted our margin of manoeuvre", an official said, adding: "We think it is the best we can we can do with the constraints we have on both sides".
May had been preparing to sell her Brexit deal to parliament, boosted by news that Europe is preparing a rapid summit to sign off on the agreement.