Some Brexit-supporting lawmakers are angry at the proposals, saying they will keep Britain tethered to the bloc and unable to change its rules to strike new trade deals around the world.
Earlier in a hastily arranged press conference before flying from the North Atlantic Treaty Organisation summit in Brussels to Britain, Mr Trump told the Prime Minister that she is not delivering the Brexit the people voted for. "The people voted to break it up so I would imagine that's what they would do, but maybe they're taking a different route - I don't know if that is what they voted for". It seems to me that there is a compelling case for expecting the value of the British Pound to rise over the coming weeks and months, with the Pound being undervalued as the market remains wary that the Prime Minister might still be thrown out of office by her own party in the meantime.
Mrs May's Conservative Party only has a majority in Parliament with the support in key votes of the 10 MPs from Northern Ireland's Democratic Unionist Party, so any split raises questions about whether her plan could survive a Commons vote - and has also led to renewed questions about whether she will face a challenge to her position. And that is fine.
In a blow to the beleaguered prime minister, Davis told May in a letter that the government's proposals for close trade and customs ties "will leave us in at best a weak negotiating position, and possibly an inescapable one". "But it is too bad what is going on", the president said.
European Council President Donald Tusk said Monday that "the mess caused by Brexit is the biggest problem in the history of EU-UK relations and it is still very far from being resolved".
"It was not the deal that was in the referendum".
The resignations came just days after May announced Friday that she had finally united her quarrelsome government behind a plan for a divorce deal with the EU.
In the wake of Mr Johnson's resignation on Monday night, members of the European Research Group of Brexiteers and the 1922 backbench committee met at separate gatherings in Westminster.
"Productive cabinet meeting this morning - looking ahead to a busy week", May said on Twitter, as the resignations of Johnson and Davis sent shockwaves through Westminster and fuelled speculation that the turmoil could eventually topple her.
"He's been very, very nice to me, very supportive", Trump said. A "high-profile battle for the Supreme Court" could help them in the fight for the House of Representatives, which is "being waged across swing suburban districts around the country".
While the president is on his military visit and holding talks with the prime minister at Chequers, Melania will be taken by the PM's husband Philip on a visit in London to meet veterans and then schoolchildren.
The UK government plan for Brexit also calls for a future customs arrangement under which Britain would collect European Union tariffs on goods bound for the bloc.
"The ambition coming from the British government to try and have a future relationship that doesn't require any border infrastructure between the United Kingdom and European Union in terms of goods and agri-food, that is one that needs to be developed through detailed negotiation".
"I think he has done a bad job on crime, if you look, all of the awful things going on there, with all of the crime that is being brought in", he said.