London (CNN) Less than 24 hours before Donald Trump is set to touch down in the United Kingdom on his first state visit to the country, the US President has sent Britain's political establishment into a spin -- telling the UK it should "walk away" from Brexit talks if the European Union does not give it what it wants.

"If you don't get the deal you want, if you don't get a fair deal, then you walk away," the President told British newspaper the Sunday Times , ahead of his three-day state visit, which kicks off on Monday.

Trump said if he were in the UK's position he "wouldn't pay" the $50 billion Brexit divorce bill, adding "it's a tremendous number."

The President also repeated his suggestion -- previously made to Prime Minister Theresa May -- that the UK should sue the EU. When asked how this would work, Trump said he would have put "on the table" the "mistakes made by the EU that cost the UK a lot of money and a lot of harm."

Trump's visit comes at a delicate time in British politics, with Westminster in a deadlock over Brexit negotiations and the clock ticking towards an October 31 exit date.

Trump: Send in Farage

Indeed Trump went as far as to say the government should send in the leader of the populist Brexit party, Nigel Farage, to negotiate with Brussels, calling him an "asset to your country."

"I like Nigel a lot and I think he's got a lot to offer," said Trump, adding that Farage was a "really terrific person" who he got to know early in his political career "when he liked my campaign and he actually came to a speech."

Farage was the first British politician to meet the new US President in 2016 -- the pair posed for a now famous photo together in a gold elevator at Trump Tower in New York.

Farage is a divisive figure in the UK. One of the most high-profile faces of the Leave campaign during the 2016 referendum, he recently made huge gains in the European elections with his newly-formed Brexit party.

But the Member of the European Parliament has also drawn scorn from Remain campaigners and EU leaders, with European Parliament liberal group leader Guy Verhofstadt previously calling Farage's salary "the biggest waste of EU resources."

London Mayor: Trump a 'global threat'

Long-time Trump critic, London Mayor Saqdiq Khan, took a swipe at the US President on Sunday, calling him "one of the most egregious examples of a growing global threat," in an interview with the Observer newspaper.

Khan said it was "un-British" to be rolling out the red carpet for a President "whose divisive behavior flies in the face of the ideals America was founded upon -- equality, liberty and religious freedom."

"In years to come, I suspect this state visit will be one we look back on with profound regret and acknowledge that we were on the wrong side of history," said the Mayor who has made no secret of his disapproval of the President.

In January last year, when Trump said he had scrapped a planned visit to the British capital because he didn't want to open the new US embassy, Khan suggested the real reason was because he wouldn't be welcome in the city.

After being delayed several times, Trump's four-day official visit to the UK last year was eventually met with large protests in London and throughout the country.

The capital's anti-Trump demonstrations featured a 20-foot "Trump Baby" blimp that flew outside Parliament -- having been given permission by Khan.

Khan, the first Muslim to be elected Mayor of London, has previously criticized the US president for his proposed travel ban on citizens from several Muslim-majority countries.

Trump: Johnson would be 'excellent' PM

Trump's latest comments come on the back of a similarly explosive interview published in British tabloid newspaper The Sun on Saturday, in which the President expressed his support for former Foreign Secretary Boris Johnson as next Prime Minister, calling him "a very good guy, a very talented person."

"I think Boris would do a very good job," the President said. "I think he would be excellent."

Trump also weighed in on comments by Meghan, now the Duchess of Sussex, ahead of the 2016 election -- back when she was better known as actress Meghan Markle.

Speaking on "The Nightly Show with Larry Wilmore," she called Trump misogynistic and said his politics were divisive, adding that she would move to Canada if he won the presidency.

Trump responded, "I didn't know that she was nasty. I hope she is OK..." But he later seemed to bury the hatchet adding, "I am sure she will go excellently (as a royal). She will be very good."