It was some poor official’s job this morning to tell Theresa May that while she slept, the relationship with the US became special for all the wrong reasons.

It is at least historic. No US president in modern times has addressed a UK prime minister with the open peevishness and contempt of Donald Trump’s tweet telling May to mind her own business.

George W Bush’s offhand “Yo Blair”, caught on an open mic in 2006, did not show much respect either, but at least it was meant to be friendly. We are a very long way away from such halcyon partnerships as Churchill-Roosevelt and Reagan-Thatcher.

Trump could not even be bothered to get May’s Twitter handle right. The diss had to be corrected.

There are many layers of humiliation here for May to get her head around over breakfast. Not only is it personally demeaning, it is also politically toxic.

The prospect of a successful or at least survivable Brexit is posited on a strong relationship with Washington. In that regard, May’s successful rush to Washington in January to become the first foreign leader received at the Trump White House was presented as a coup.

Under EU rules, the two countries are not allowed even to start negotiating a trade deal until the UK is truly out of Europe, but the warm words and the pictures of the Trump and May holding hands at least struck an encouraging tone. The prime minister got to Washington in time to help the state department and Congress stop the president lifting sanctions on Russia, and squeezed out of him his first grudging words of support for Nato.

It has been downhill since then.

May had to tell the president off in September for speculating about a terrorist attack in London. On Wednesday she had little choice but to rebuke him for retweeting Islamophobic videos put out by the UK far right, and that earned her the acid riposte from the thin-skinned president on Wednesday night.

So what can May do to limit the damage? She can be stern or she can try to laugh it off. But whichever mode she adopts, she will have to distance herself from Trump in the short term while sending reassuring noises that all will be fine in the long term.

All the signs suggest however, that it will not be fine.

May is in open disagreement with Trump over a major foreign policy issue, the nuclear deal with Iran, which the president would like to destroy and which the UK is anxious to salvage. To that end, May’s strongest card is European solidarity. Top diplomats from the UK, Germany and France are in Washington this week to do a triple act in defence of the agreement.

The Europeans are also desperate to steer the Trump administration from the path to war with North Korea, that is being paved with the help of Trump’s sound-bite bellicosity.

The irony is that it is just such European unity of purpose that May is committed to undermine. Having a US president who is so erratic and extreme that he makes disagreements with EU seem petty by comparison is a bad look for a prime minister championing Brexit.

As for Trump, there is no convincing evidence he cares much about the UK relationship anyway. He is more drawn to autocracies such as Saudi Arabia and China. Having a Scottish-born mother has not made him sufficiently sentimental that he would grant the UK a speedy and favourable trade deal after Brexit. He has built his whole political persona on being unyielding in such negotiations.

As the special counsel investigation into collusion with Moscow advances into the White House, and as one after another of the administration’s legislative initiatives fall flat, Trump is withdrawing further and further into his base, which is resentful of the liberal world order and indifferent to old European ties.

If it were not already clear, the latest presidential tweet leaves little doubt. Theresa May does not a have partner, or even a friend, in the White House.