WASHINGTON — The setting was the annual dinner of the American Enterprise Institute, a tony affair on Thursday featuring 1,500 exuberant believers in free enterprise, limited government and the superiority of American values.
The question for Boris Johnson — former mayor of London, former British foreign secretary and current potential British prime minister — was simple:
What’s the worst mistake you’ve ever made?
There were many possibilities to choose from. But Mr. Johnson looked at his interlocutor, Arthur C. Brooks, the institute’s president, and developed the glint in his eye that usually means he is about to deploy a well-rehearsed bluster-and-deflect response.
“My strategy is to litter my career with so many decoy mistakes, nobody knows which one to attack,” Mr. Johnson declared. “In the last few minutes I’ve probably said something that the British media will say is absolutely outrageous, though I don’t know what it is.”
What Mr. Johnson did not mention was the cloud of intrigue, both personal (he is about to get a divorce) and political (he is probably plotting against Prime Minister Theresa May), wafting around him as he made his way across the Atlantic.
Articulate, charismatic and virtually unembarrassable, Mr. Johnson is one of the most popular leaders in a Conservative Party riven by internal dissent — and one of the few British politicians who is instantly recognizable to a foreign audience.
Along with Nigel Farage — the deeply anti-Europe U.K. Independence Party politician who used to be seen as a bit of a joke in Britain but has been touted by President Trump as someone whom “many people” believed should be ambassador to the United States — Mr. Johnson is emerging as the sort of leader Mr. Trump likes.
During his visit to Britain this summer, the president declared that Mr. Johnson would “make a great prime minister” because, he said, “he’s got what it takes.”
And Mr. Johnson, who once called Mr. Trump “stupefyingly ignorant,” “clearly out of his mind” and unfit to be president, has lately taken to praising him back.
“I have become more and more convinced that there is method to his madness,” he was quoted as having said at a private meeting of Conservatives in June.
At home, Mr. Johnson is seen as a deeply ambitious opportunist who masks his seriousness of purpose with a well-polished air of befuddled dishevelment and humorous nonchalance.
Like many Trumpian Republicans, Mr. Johnson has lately been tacking right, employing (in his case) an increasingly populist tone on issues like immigration, multiculturalism and Brexit, as the difficult process of Britain’s extrication from the European Union is called.
Moderate Conservatives regard him as stealthy and dangerous.
“The cheeky chap of ‘Have I Got News for You?’ has morphed into a snarling populist,” the Conservative commentator Matthew d’Ancona wrote recently, referring to a satirical game show that Mr. Johnson occasionally appeared on earlier in his career. “We need to approach his ambitions with deadly seriousness.”
None of that was mentioned in Washington, where Mr. Johnson, 54, was in town to accept this year’s Irving Kristol Award, which honors people who have made “exceptional intellectual and practical contributions to improve government policy, social welfare, or political understanding.” Previous recipients include Benjamin Netanyahu and Paul Ryan.
Answering questions onstage from Mr. Brooks — sample: “Tell us, what does the special relationship mean, in your view?” — he discussed Russia, Europe, Winston Churchill, the Roman Empire and how the best way to promote unity in a Britain divided by discord over Brexit would have been for England to beat France in the World Cup.
Discussing his political evolution, Mr. Johnson described how his encounters with “bourgeois affluent hypocritical left-wing students” at Oxford University proved so unpleasant that he underwent a political conversion, virtually on the spot.
“My right-wing feelings were triggered, to use a modern word, by my sense of outrage at their glutinous hypocrisy,” he said, speaking of his classmates.
While describing the need for what is known as “hard Brexit” — one without concessions to Europe — Mr. Johnson studiously avoided the topic of the trouble he has been stirring up back home.
He noisily resigned as foreign secretary in July, saying that he disagreed with what he sees as Mrs. May’s too-conciliatory approach to Europe. Since then, he has made a series of deliberate provocations against the prime minister while presenting himself, even more than usual, as a plain-talking person of the people, eager to tell it like it is.
Writing this summer on the topic of European democracies’ banning burqas, he said that while women should wear whatever they liked, wearing a burqa was akin to dressing as a “bank robber.”
“It is absolutely ridiculous that people should choose to go around looking like letter boxes,” he wrote, a reference to the thin slots in mailboxes into which people put the mail.
That proved irksome to Mrs. May.
“It’s very clear that the language Boris Johnson used to describe people’s appearance has caused offense,” she said crossly. “It was the wrong language to use, and he should not have used it.”
That was not all. Mr. Johnson recently wrote that Mrs. May’s Brexit plans, which he believes would leave Britain too beholden to Europe, made Britain look like “a seven-stone weakling being comically bent out of shape by a 500-pound gorilla.”
He added, speaking of Europe’s Brexit negotiator: “We have wrapped a suicide vest around the British Constitution — and handed the detonator to Michel Bernier.”
That proved irksome to more people than just the prime minister.
“This marks one of the most disgusting moments in modern British politics,” Sir Alan Duncan, a Conservative member of Parliament and a minister in the Foreign Office, wrote on Twitter.
Dominic Grieve, a Tory moderate, said that the remark was “entirely in character: crude but, for some, entertaining populist polemic.”
Basking in the Washington audience’s admiration of his erudition, discussion of history and robust lack of self-consciousness, Mr. Johnson did not seem particularly bothered by this, or much of anything, on Thursday. But asked about his political aspirations in a brief conversation with The New York Times, he looked fake-pained at the presence of a reporter’s notebook.
“Put that away,” he said, running his fingers through his hair, still shockingly blond and still emitting the appearance of having been dropped onto his head with no coherent plan for what to do when it got there.
Asked if his remarks about Russia, which he had just denounced from the stage as a regime that cannot be trusted, carried an implicit criticism of Mr. Trump, he said that on the contrary, they absolutely did not.
“No, no, don’t write that,” he said. “I don’t want to make him angry.”
For all the people who are angry at him back home, there are also those who think he is wonderful. His remarks about the burqas, for example, prompted a round of let-Boris-tell-the-truth letters in the pro-Boris Daily Telegraph.
“A strength of English culture is our propensity to laugh at ourselves, whether at Colonel Blimp or burqa-wearing Muslim women,” wrote a reader who signed his name “The Rev. His Honor Peter Morrell.”
Another reader, David Waller from Shropshire, said: “Personally, I think the archbishop of Canterbury looks a complete idiot in his tea cozy and his grandmother’s curtains.”
And Andrew Nichols from Hertfordshire, borrowing the language of the American right, wrote: “It might be heading toward the hottest summer on record, but the snowflakes are clearly still flourishing.”