But note that Sanders quoted Trump while asserting that he "never said anything bad about her".
The white paper, outlining proposals for the UK's stance with the European Union, is being regarded as signalling a "soft Brexit" which Trump had told the Sun could "kill" a free trade deal with the US.
Yesterday, Trump fanned the flames by giving Rupert Murdoch's Sun tabloid an exclusive interview where he blasted May's policies and threatened to take a U.S-U.K trade deal off the table over the Brexit development.
Last week at the same location, May finally won agreement for her Brexit plans from her cabinet but within days two senior ministers had quit, departures which Trump said earlier in the week had left Britain in turmoil.
He is planning to meet with Russian President Vladimir Putin next week.
However, he later said Ms May was doing a "fantastic job".
"She is a very smart, very tough, very capable person, and I would much rather have her as my friend than my enemy". Today we're talking trade, we're talking military, some incredible anti-terrorism things and the relationship is very very strong.
Some carried placards saying Special Relationship?
"It would be better if [the London Mayor] stopped engaging in this war against Donald Trump and got on with ... dealing with the crisis in crime", Farage said, pointing to the vicious attack on former British ambassador to the U.S. Sir Christopher Meyer Wednesday, which took place at one of the capital's major railway stations in broad daylight.
In the interview, Trump described Johnson as "a very talented guy", adding: "I like him a lot. She might well do what I suggested that she might want to do but it is not an easy thing".
However, while Trump and May exchanged warm words, tens of thousands of protesters marched against the USA president through central London, bringing much of the British capital to a standstill.
"He does listen to her, he does have, I think, a genuine respect for the United Kingdom and for the office that she holds".
"The reaffirmation of the British-U.S. relation we saw at the press conference will probably assuage some of the doubts we have seen about the status of the relationship", Parakilas said.
Meanwhile, tens of thousands of protesters marched against the USA president through central London, bringing much of the capital to a standstill. It was one of the more than 100 demonstrations planned across the country during his four-day stay.
The president in the interview denied that he ever "said anything bad about" May in the interview after The Washington Post reported that he thinks the British leader is a "bossy schoolteacher".
"I said Brexit will happen and it did happen", he added.
Before heading for Scotland, the president and Queen Elizabeth II became acquainted over tea at Windsor Castle.