It is all too easy to compare the new prime minister of Britain to President Trump. Boris Johnson has a similar mop of blond hair — he has even said he was once mistaken for Trump — hails from the right-leaning party in Britain and has spearheaded a nationalist movement that has rocked the Western alliance. And all signs point to a more simpatico diplomatic relationship than the occasionally rocky one Trump has had with Johnson’s predecessor, Theresa May.

But it wasn’t always so. In fact, Johnson’s past criticism of Trump was at times even more pitched than that of many of the Republicans who derided Trump in 2016, then just a Republican presidential candidate, as dangerous and unhinged — and have since come around to support him.

Much has been made of Sen. Lindsey O. Graham’s (R-S.C.) convenient and often-dumbfounding transformation from Trump denouncer to top Trump ally, but Johnson’s conversion bears plenty of similarities.

The most-trafficked Johnson quote about Trump came after Trump wrongly said in 2015 that there were “no-go” zones in London where police wouldn’t go because of Muslim extremists. Johnson, who at the time served as mayor of London, said Trump demonstrated “a quite stupefying ignorance that makes him, frankly, unfit to hold the office of president of the United States.” Johnson was reportedly the first senior British politician to declare Trump unfit for the presidency.

“I would invite him to come and see the whole of London and take him round the city,” Johnson added, “but I don’t want to expose Londoners to any unnecessary risk of meeting Donald Trump.”

That’s a theme to which Johnson has returned. At another point, he said that “the only reason I wouldn’t go to some parts of New York is the real risk of meeting Donald Trump.” He has also said of visiting New York (where Johnson was born): “Some photographers were trying to take a picture of me, and a girl walked down the pavement towards me and she stopped and she said, ‘Gee, is that Trump?’ It was one of the worst moments.”

When Trump proposed a Muslim immigration ban in the United States, Johnson called it “complete and utter nonsense” and said, “I think Donald Trump is clearly out of his mind.”

He has even compared Trump’s tactics to the extremists Trump was allegedly trying to root out. “What he’s doing is playing the game of the terrorists and those who seek to divide us,” Johnson said. “That’s exactly the kind of reaction they hope to produce.”

And when Trump neared the GOP nomination in spring 2016, Johnson said, “I am genuinely worried that he could become president."

Some of this has less to do with Trump than it does with Johnson, who before becoming British foreign minister in 2016 made a habit of attacking foreign leaders and not mincing words. He at one point called George W. Bush “a cross-eyed Texan warmonger, unelected, inarticulate, who epitomizes the arrogance of American foreign policy.” When a bust of Winston Churchill was removed from Barack Obama’s Oval Office (along with others), Johnson derided it as “a symbol of the part-Kenyan President’s ancestral dislike of the British empire — of which Churchill had been such a fervent defender.” In 2012, he hit back at then-GOP presidential nominee Mitt Romney — whom he dismissively deemed “a guy called Mitt Romney” — for questioning London’s readiness for the upcoming Olympics.

Johnson has since telegraphed a softer approach to Trump, but there are already signs that could be tested. When Trump recently urged four nonwhite congresswoman to “go back” to their countries — even though three of the four are not immigrants — Johnson called it “completely unacceptable.” And Trump hasn’t exactly been shy about poking the top U.S. ally, leading to the occasional rebuke from May.

Johnson also has been criticized for being too deferential — even sycophantic — toward Trump. That’s a criticism many of Trump’s GOP allies have weathered too, but they have very different constituencies to answer to than does Johnson. And given Johnson seems to have said what he really thinks about Trump in the past, it will be fascinating to see how he threads the diplomatic needle.