Trump and May talk to the media on July 13.
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 USA trade deal.
However, addressing the press at Chequers, Trump said "didn't criticise" May in the interview, insisting he had a "lot of respect" for her.
Trump said: "The relationship between our two nations is indispensable to the cause of liberty, justice, and peace".
In an interview with The Sun newspaper, Trump criticized May's "soft Brexit" plan and said Boris Johnson, a May rival who resigned his position as foreign minister over her Brexit plans, would make an "excellent" prime minister. I gave her a suggestion, not advice. I am not sure.More news: Congress to Trump: Cancel Putin summit after new Mueller indictments
Trump has insisted the US-UK relationship is "the highest level of special". "We wanted to embarrass him and I think we have done that today".
A trade deal with the U.S. is supposed to be the big prize of Brexit, with its potential to largely compensate the economic loss that would ensue by exiting the European single market. "This is an incredible opportunity for our two countries and we will seize it fully", he said.
"It was from right here at Chequers that Prime Minister Churchill phoned President Roosevelt after Pearl Harbor", Trump said, referencing the surprise attack by the Japanese on December 7, 1941, that plunged the USA into World War II.
I am just saying I think he would be a great Prime Minister.
If the United Kingdom remains too tethered to the 27 remaining European Union countries, it could hinder their trade deals with other nations, she warned.More news: Wimbledon 2018: Serena Williams to face Angelique Kerber in women's final
Tom Swarbrick, former adviser to Theresa May, told Euronews that Trump's comments were "the worst possible start to the trip". "I actually told Theresa May how to do it, but she didn't listen to me".
"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.
"This incredible woman right here is doing a fantastic job", he said. "She's a total professional, because when I saw her this morning I said, 'I want to apologize, because I said such good things about you"'. "She said: "Don't worry, it's only the press". It was one of the more than 100 demonstrations planned during his four-day stay.
There were also demonstrations close to Winfield House, the United States ambassador's residence near Regents Park where the president and first lady Melania Trump have spent the night. The American First Couple were then due to travel to Windsor for a meeting with the Queen before flying to Scotland where they plan to spend the weekend. Trump and his wife spent nearly an hour with the 92-year-old monarch, staying 17 minutes after their expected departure time.More news: British Diver Who Helped Rescue Trapped Boys in Thailand Returns to UK