WASHINGTON — Just before his state visit to Britain was to begin, President Trump subverted diplomatic norms by rattling an already precarious political situation there: He suggested that the next prime minister of Britain “walk away” from trying to reach a deal to withdraw from the European Union and that the far-right populist Nigel Farage be sent in to negotiate.
In an interview with The Sunday Times, of London, Mr. Trump also said he had told the current prime minister, Theresa May, who announced last month that she would step down after repeatedly failing to get her Brexit plan through Parliament, to sue the bloc for greater leverage in talks. Mrs. May left her government in a weaker position, he said, for not threatening to walk away “in the form of litigation or in the form of a request.”
The president and Melania Trump, the first lady, are set to arrive in London on Monday for a full state visit, which Mrs. May had been trying to arrange for years. Coincidentally, it will be her last week as the leader of the Conservative Party. With the government five months away from an exit deadline, uncertainly looms over her potential successor. The British economy has also taken several hits, which businesses have blamed on Brexit.
Across the Atlantic, Mr. Trump’s comments only reinforced the degree of instability.
In the interview, the president posed the idea that Mr. Farage, the leader of the newly founded Brexit Party who has been a battering ram to traditional conservative politics in Britain and a rival and irritant to Mrs. May, should take over the negotiations.
Mr. Trump, who once suggested that Mr. Farage become ambassador to the United States, praised him as a “very smart person” who could help guide Britain after its decision to leave the European Union. Mr. Farage has backed such a departure for decades.
“I like Nigel a lot. He has a lot to offer,” Mr. Trump said. “He is a very smart person. They won’t bring him in. Think how well they would do if they did. They just haven’t figured that out yet.”
Eyeing the cast of possible replacements for Mrs. May, Mr. Trump said Boris Johnson, the former mayor of London and foreign secretary, would make an “excellent” prime minister. And confronting the possibility that the Labour leader Jeremy Corbyn could win an election in the next year, the president said he would have “to know” Mr. Corbyn before sharing state secrets.
Queen Elizabeth II will host the Trumps in an arrival ceremony at Buckingham Palace, with a state dinner to follow, White House officials said. Mr. Trump will then hold a bilateral meeting with Mrs. May on Tuesday.
On a phone call with reporters before the visit, White House officials stressed that, despite Mrs. May’s impending departure, there were “many things for them to still talk about” on the bilateral agenda, including trade and security.
But not even the British royals, who will be among the first to receive Mr. Trump in England, were off-limits from Mr. Trump’s running commentary. In a separate interview, the president told The Sun that he had been unaware that the Duchess of Sussex, formerly known as Meghan Markle, had made “nasty” comments about him during the 2016 presidential campaign.
“I didn’t know that,” Mr. Trump said. “What can I say? I didn’t know that she was nasty.”
The president added that he hoped she would make a “very good” princess.