But in the not-so-distant past, such a relationship appeared highly unlikely—if not outright impossible. “I think Donald Trump is clearly out of his mind,” Johnson, who was at the time the mayor of London, said of then-candidate Trump’s 2015 call to ban Muslims from entering the United States. In response to the Republican hopeful’s early criticisms of London, which Trump erroneously described as having “no-go areas” teeming with Islamic extremism, Johnson said Trump betrayed “a quite stupefying ignorance that makes him, frankly, unfit to hold the office of president of the United States.”
On the prospect of a Trump visit to London, Johnson said he would welcome the president, “except that I wouldn’t want to expose Londoners to any unnecessary risk of meeting Donald Trump.” In some ways, Johnson’s thoughts about Trump when he served as London mayor were similar to those of his successor to that position, Sadiq Khan.
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London’s mayor may have changed, but Trump’s attacks on the British capital haven’t relented since he entered the White House. In fact, the president has taken his criticisms of the city even further—this time though a years-long Twitter feud with Khan. A “stone cold loser” is how Trump described Khan before touching down in London for his state visit this month. Weeks later, the president amplified a tweet by a right-wing British commentator who described weekend violence in the city as a product of “Khan’s Londonistan.” The president’s tweet was condemned by most of the Conservative Party leadership candidates. (Johnson didn’t comment.)
Johnson’s recent unwillingness to publicly spar with Trump could be regarded as the behavior of a prime minister in waiting. As the leading candidate to be the next custodian of the “special relationship” between the U.S. and the U.K., Johnson has no incentive to do anything that could further aggravate tensions between the two countries—especially if it means sacrificing the possibility of striking a U.S.-U.K. trade deal. Should Brexit happen by the end of October, as Johnson has advocated, that relationship will be more crucial than ever to Britain.
Read: The U.S.-U.K. alliance has seen better days
But the relationship could be warming for other reasons. After all, there are plenty of similarities between the two men: They both have roots in New York City (Johnson was born in Manhattan’s Upper East Side, just across the river from Trump’s native Queens). Both sport trademark disheveled hairdos. And both have crafted political personas that feed off their own celebrity: For Trump, it’s his high-profile career as a real-estate mogul; for Johnson, it’s his public image as a bumbling politician always stumbling (or zip-lining) from one gaffe to the next.
Beyond the superficial, each has established patterns of governance that would make the other a strong ally. They have run nationalist campaigns that appealed to the grievances of those who have felt left behind in their respective countries. And both have made false claims in pursuit of their aims: Johnson pledged that a vote for Brexit would save the country £350 million ($470 million) per week to invest in Britain’s National Health Service, and Trump promised that Mexico would pay for the wall at the U.S.’s southern border. Neither Johnson nor Trump has shied away from saying offensive things—most notably toward Muslims and other minorities—along the way.