Standing next to the Prime Minister at a press conference at Chequers, the President shifted his stance from that in The Sun's world exclusive interview where he warned a softer Brexit would "probably kill" a U.S. trade deal.
It had been widely assumed that he had suggested she walk away from the talks, but Mrs May told BBC1's Andrew Marr Show that the US President had encouraged her to take the entire European Union to court.
"I'm saying that now so that when I go into negotiations with you people, I'm going to try and top you, you're going to try and top us".
"I'm sure Theresa May doesn't want to split the Conservative Party and therefore she will find that the inevitable outcome of the parliamentary arithmetic is that she will need to change it to keep the party united".
In an interview with The Sun newspaper published Thursday - just as May was hosting Trump at a lavish black-tie dinner - Trump said the British leader's approach likely "killed" chances of a free-trade deal with the United States.
"Actually, no, we're going into negotiations with them", she said, referring to the EU. On the one hand it what would have been for us a very poor trade deal and would have kept Northern Ireland in the customs union, effectively carving Northern Ireland out in these terms of the UK.
Not so she says, it had been "in gestation for some time".
"I am just saying I think he would be a great Prime Minister".
The colourful Boris Johnson quit rather than take part in turning Britain into a "colony", after May's blueprint for Brexit was signed off by her cabinet.
He added: "92% of our economy is the services sector, we need to make sure not simply is there a deal in relation to goods during post transition, we need a back stop in relation to services..."
This morning, May revealed that advice was to sue the EU.
"We are stuck. In any rational world, and I understand that is a big caveat in today's politics, this would go back to the people for resolution".
"The European Commission' proposals that it put forward were no good".
'We'll make everything possible if the president wants to do something, ' he added.
He also labeled the interview with The Sun as fake news and said it did not include the positive things he had said about the prime minister.