The so-called “special relationship” looks especially imperilled on Monday after Donald Trump took to Twitter to slam Theresa May and announce that his administration would no longer deal with the UK’s ambassador to Washington, Kim Darroch. The tweet followed remarks critical of Trump made by Darroch, which were leaked in the Mail on Sunday.

“I have been very critical about the way the UK and Prime Minister Theresa May handled Brexit,” the president tweeted. “What a mess she and her representatives have created. I told her how it should be done, but she decided to go another way. I do not know the Ambassador, but he is not liked or well [...] thought of within the US. We will no longer deal with him.”

“The good news for the wonderful United Kingdom is that they will soon have a new Prime Minister,” Trump added. “While I thoroughly enjoyed the magnificent State Visit last month, it was the Queen who I was most impressed with!”

Earlier on Monday, May had said she had “full confidence” in Darroch. But her successor as Prime Minister – whether that is Boris Johnson or Jeremy Hunt – will now face the tricky task of replacing him.

This could be as much of an opportunity as a danger. Trump has previously expressed interest in the idea of Nigel Farage being the UK’s ambassador to the US; that idea might seem preposterous on its face, though conceivably a newly-crowned Prime Minister Boris might see it as an opportunity both to neutralise a political opponent and to install in Washington an ambassador with a personal relationship with the US president.

But much more likely, the leaks – in which Darroch is revealed to have described the Trump administration (accurately and, if anything, generously) as “inept” and “dysfunctional” – will further damage any chance for a post-Brexit Britain of leveraging the “special relationship” with the US into a beneficial transatlantic trade deal. Trump’s visit to the UK in June was marked with widespread protests, and while Trump was clearly impressed with the pomp and circumstance of meeting with the Queen, it is unlikely that will translate into meaningful policy.

Worse, Trump’s intervention highlights the incredibly awkward position in which the president’s statedly pro-Brexit position puts the British government . He identified himself as pro-Brexit, but made clear today that if it’s not executed on his terms – and, since his understanding of the situation is desperately limited, those terms are likely to revolve around what would be a PR coup for him personally – his support cannot be counted on..

With Trump’s approval rating in the UK so low, it is almost inconceivable that any likely outcome of Brexit would carry the kind of pro-Trump public perception – or, more accurately, the performance of such perception – that could possibly flatter Trump enough that he would play ball.