Donald Trump’s rapid-fire praise of Boris Johnson’s victory will be one the next prime minister will gladly welcome with the upcoming challenges over Brexit.
But the new Tory leader, eager to strengthen the transatlantic relationship in anticipation of a trade deal, will hope the US President does not dwell on his past barbs.
These include accusing Mr Trump of “stupefying ignorance”, and saying he was “out of his mind” and “unfit” to lead the States.
And while the deeply-desired deal is one Mr Johnson will champion, dealing with the US President may also be one of his greatest challenges after Brexit, as repeatedly learned by Theresa May.
It took a matter of minutes for the US President to use his favourite medium to celebrate Mr Johnson’s victory on Tuesday.
“Congratulations to Boris Johnson on becoming the new Prime Minister of the United Kingdom. He will be great!” he tweeted.
Days before Mr Trump had lavished praise on Mr Johnson as he anticipated his victory and a “very good relationship” to come.
“I like him. I like Boris Johnson. I always have. He’s a different kind of a guy but they say I’m a different kind of a guy too. We get along well,” he told reporters.
But whether that warm relationship was always reciprocated is revealed by Mr Johnson’s past comments.
As London mayor in 2015, he described Mr Trump as “clearly out of his mind” and “unfit” for the White House when the then-presidential candidate called for a ban on Muslims entering the US.
“What he’s doing is playing the game of the terrorists and those who seek to divide us,” Mr Johnson continued.
“When Donald Trump says there are parts of London that are no-go areas, I think he is betraying a quite stupefying ignorance that makes him frankly unfit to hold the office of the President of the United States.”
Mr Johnson joked: “I would invite him to come and see the whole of London and take him round the city, except that I wouldn’t want to expose Londoners to any unnecessary risk of meeting Donald Trump.”
Critics now accuse the leaders of similarities, accusing them both of a proclivity for falsehoods and bombastic language.
Back in March 2016, Manhattan-born Mr Johnson described being mistaken for his fellow blond in New York as “one of the worst moments”.
And he previously ridiculed the tycoon by saying “the only reason I wouldn’t go to some parts of New York is the real risk of meeting Donald Trump”.
Mr Johnson, who will become PM on Wednesday, has since changed his tack on the president.
As Foreign Secretary in 2016 he told Europeans to cease their “collective whinge-o-rama” over the tycoon’s triumph.
And in the leadership campaign Mr Johnson praised the President as having “many, many good qualities” and celebrated him for having “got the US economy motoring along”.
He was also very cautious not to stray too far from the President’s thinking, or criticise him too severely.
Mr Johnson was accused of having thrown ambassador to the US Sir Kim Darroch “under the bus” when he refused to say whether he would keep him in his post amid intense criticism from the President.
The following day Sir Kim resigned, outraging the diplomatic world.
And, while criticising Mr Trump’s “go back” remarks to four congresswomen as completely unacceptable, he refused to call them racist, as many others did.
But Mr Johnson did demonstrate his willingness to differ from the President when it came to issues such as Iran, saying in the campaign that he supports diplomatic efforts for the time being.
Asked if he would back the US on an intervention, he said he does not believe war is a “sensible option”.
Mr Johnson will hope he can maintain the close ties he currently has achieved with the American leader.
But, as Mrs May learned, the President’s praise can turn into insults with the click of a button.
…handled. I told @theresa_may how to do that deal, but she went her own foolish way-was unable to get it done. A disaster! I don’t know the Ambassador but have been told he is a pompous fool. Tell him the USA now has the best Economy & Military anywhere in the World, by far…
— Donald J. Trump (@realDonaldTrump) July 9, 2019
A month after his state visit, Mr Trump tweeted criticism of her Brexit negotiations and accused her of having gone “her own foolish way”.