Donald Trump has declared that the UK is “in turmoil” amid a spate of ministerial resignations over Brexit, and suggested that his meeting with Russian president Vladimir Putin would be the easiest of his trips to Europe.

Mr Trump, speaking as he left Washington for his week-long trip, which includes meeting with Nato leaders and Theresa May, offered little support for the embattled UK prime minister.

Speaking as he and wife Melania boarded Marine One outside the White House, Mr Trump said: “It’s going to be an interesting time in the UK and an interesting time at Nato. We will work it out and all countries will be happy.

“So I have Nato, I have the UK – which is in somewhat turmoil. And I have Putin. Frankly, Putin may be the easiest of all.”

With Ms May facing the culmination of months of unrest within her own Conservative Party over the negotiations for Britain to leave the EU, Mr Trump offered few words of reassurence.

Instead the US president told reporters that Boris Johnson – the second of Ms May’s Cabinet ministers to quit within 24 hours – was a “friend”.

A history of presidential visits to the UK: in pictures Show all 15 1 /15 A history of presidential visits to the UK: in pictures A history of presidential visits to the UK: in pictures The first President to visit Britain was Woodrow Wilson, who is pictured here with King George V at Buckingham Palace in 1918 PA A history of presidential visits to the UK: in pictures President Wilson also ventured up to Carlisle, home to several of his ancestors Getty A history of presidential visits to the UK: in pictures President Dwight D. Eisenhower waves to spectators as he is driven down Fleet Street on his visit in 1959 Getty A history of presidential visits to the UK: in pictures Eisenhower had visited Britain previously as General Eisenhower, commander of the Allied forces In Europe during the Second World War. He was awarded Freedom of the City of London on 12 June 1945 Getty A history of presidential visits to the UK: in pictures President John F. Kennedy visited in 1961 and later in 1963 PA A history of presidential visits to the UK: in pictures The visit of President Richard Nixon in 1969 led to protests on the streets of London. His presence was controversial due to America's actions in the Vietnam War PA A history of presidential visits to the UK: in pictures President Jimmy Carter was warmly received on his visit in 1977. He was made a Freeman of the city of Newcastle, where he visited to formally twin the city with Atlanta, Georgia PA A history of presidential visits to the UK: in pictures President Ronald Reagan rode horses with the Queen on his first visit in 1982 PA A history of presidential visits to the UK: in pictures Getting along famously with Margaret Thatcher, Reagan visited multiple times and once addressed the House of Commons PA A history of presidential visits to the UK: in pictures President George H.W. Bush is pictured on his 1989 visit, where he went through the formalities PA A history of presidential visits to the UK: in pictures President Bill Clinton visited many times throughout the 1990s, starting on a high note as he received an honorary degree from Oxford on his first trip in 1994. He is pictured here in a meeting with Blair's Cabinet in 1997 AFP/Getty A history of presidential visits to the UK: in pictures President George W. Bush visited multiple times. He is pictured here on his first trip reading to children in the British Museum, or at least First Lady Laura Bush is PA A history of presidential visits to the UK: in pictures President Barack Obama was popular with the British public, perhaps that's why he and Gordon Brown could safely walk along a public street in Westminster in 2008 PA A history of presidential visits to the UK: in pictures Obama also visited during David Cameron's time as Prime Minister, as well as table tennis, they played golf and had a family barbecue PA A history of presidential visits to the UK: in pictures President Obama's final visit in April 2016 was controversial, as he endorsed Britain's remaining in the European Union at the height of the Brexit campaign PA

“Boris Johnson is a friend of mine, he’s been very, very nice to me, very supportive. And I maybe will speak to him when I get over there. I like Boris Johnson, I’ve always liked him,” Mr Trump said.

Last month, leaked remarks from Mr Johnson suggested that Mr Trump would be able to do a better job of negotiating Brexit than Ms May.

“I am increasingly admiring of Donald Trump,” the former foreign secretary said. “I have become more and more convinced that there is method in his madness.”

Theresa May jeered in House of Commons after Davis and Johnson resignations

“Imagine Trump doing Brexit,” he went on. “There’d be all sorts of breakdowns, all sorts of chaos. Everyone would think he’d gone mad. But actually you might get somewhere. It’s a very, very good thought.”

Mr Trump’s visit on Friday, which is sure to attract protests across the country, will add to the pressure on Ms May, who has seen both Mr Johnson and former Brexit secretary David Davis leave her government since Sunday.

Commenting on Ms May’s position, Mr Trump said that the UK “certainly has a lot of things going on”.

Asked whether Ms May should be replaced as prime minister, the US president replied: “Well that’s up to the people. I get along with her very well, I have a very good relationship. That’s certainly up to the people, not up to me.”

Mr Johnson said in his resignation letter that Ms May was proposing a “semi-Brexit.” Contact with him by Mr Trump during his visit would be seen by many as an insult to Ms May.

“Brexit should be about opportunity and hope,” Mr Johnson said in his letter to May on Monday. “That dream is dying, suffocated by needless self-doubt.”

The relationship between Ms May and Mr Trump have been strained at times, since he entered the White House. There have been clashes over US tariffs on steel and aluminium as well as comments Mr Trump made about the level of knife crime in London.

The enduring image of Ms May’s visit to the White House in January 2017, when she became the first foreign leader to meet the president after he took office, was Mr Trump taking Ms May’s hand to help her down the steps of the White House colonnade. That sought to show the two nations were still on strong terms, but this week’s visit is set to be a little more strained.

Before he meets Ms May, Mr Trump will attend a Nato summit in Brussels. After his UK visit, the president will head to Helsinki to meet with Mr Putin, both of those visits will pose their own challenges for Mr Trump.

The potential diplomatic embrace for Mr Putin, will do little to reassure Mr Trump’s Nato allies of his commitment to the 69-year-old transatlantic mutual defence pact.

Mr Trump said as he was leaving Washington on Tuesday that he “can’t say right now” if Mr Putin is a friend or foe, but called him a “competitor”. The US intelligence community has concluded that Russia interfered in the 2016 election to boost Trump’s candidacy, and warns of further attempts at interference both in the 2018 midterms and in European elections.

Since his election campaign in 2016, Mr Trump has also criticised his Nato allies for placing too much of the financial burden for the alliance on the US. On Tuesday Mr Trump again hit out at the pact, saying: “Frankly it helps them a lot more than it helps us.”

Mr Trump has been pressing Nato countries to fulfil their goal of spending two per cent of their gross domestic products on defence by 2024. During his presidential campaign, he suggested he might only come to the defence of Nato nations that fulfilled their obligation.