During the presidential election the Huffington Post’s US site carried the following editor’s note at the end of every story about the Republican nominee: “Donald Trump regularly incites political violence and is a serial liar, rampant xenophobe, racist, misogynist and birther who has repeatedly pledged to ban all Muslims – 1.6 billion members of an entire religion – from entering the US.”

Shortly before 6am on that long election night – in between Trump’s winning Iowa and being declared the victor in Pennsylvania – the Washington bureau chief announced that the note would be removed, “in respect for the office”, and that it was time for a “clean slate”.

A year before his election, Fiona Hill, who would become one of Theresa May’s joint chiefs of staff, tweeted: “Donald Trump is a chump #trumpisachump”. Six months later Nicholas Timothy, who would become May’s other joint chief, wrote: “As a Tory I don’t want any ‘reaching out’ to Trump.” Once Trump was elected, however, May couldn’t reach out fast or far enough – the first foreign leader to meet the president, just a week after his inauguration.

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During the primaries former Republican presidential hopeful Mitt Romney tweeted: “If Trump had said 4 years ago the things he says today about the KKK, Muslims, Mexicans, disabled, I would NOT have accepted his endorsement.” Almost two years later, Romney decided to run for the Utah senate seat and Trump endorsed him. “Thank you Mr President for the support,” he responded.

According to Tim Shipman’s account in Fall Out, a month before the US election the foreign secretary Boris Johnson told a friend: “This is an election that is going to expose America’s primal pysche as never before. If it is Trump, it will be a victory of really base daytime TV Redneck America.” Last month there was Johnson, on breakfast TV (Fox & Friends) insisting that Trump could be a candidate for the Nobel peace prize, as he unsuccessfully pleaded with the president, via one of his favourite TV shows, not to abandon the Iran nuclear deal.

Power can apply a soothing balm to a raging conscience. In its absence, all kinds of moral positions can be staked out in bold, vivid rhetoric. But it is only in the presence of power that these values are tested. For it is only then that there is a price to pay. In those moments we see whether the lines people have drawn have been carved in stone, so they can stand by them, or etched in sand, ensuring no permanent trace.

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So it has been with Trump’s elevation. Once his candidacy proved viable there was a broad consensus that it should not be normalised. This was not simply a politician with whom some had policy disagreements; here was a man who practised a style of politics that could not be indulged. He advocated violence at his own rallies, branded journalists scum, brazenly invented facts, employed unvarnished racism, xenophobia and misogyny on the stump and refused to accept the result if he lost. To treat him like any other candidate would be not only to legitimise such political behaviour but reward it. That is why it will be important to demonstrate during his July visit to make clear to the world that we have clear moral lines and the man who is ostensibly our main ally has crossed them many times.

This was no partisan beef – initially, mainstream conservatives, on both sides of the Atlantic, said they wanted nothing to do with him. Then he won. Those on the right, trading principle for pragmatism and the certainty of aggravation for the possibility of access, accommodated, adapted and soon fell in line as though the line were their idea. “What concerns me about the American press is this endless, endless attempt to label the guy as some kind of kook not fit to be president,” South Carolina senator Lindsey Graham told CNN last November. Graham apparently forgot that he’d told Fox the year before, “I think he’s a kook. I think he’s crazy. I think he’s unfit for office.” Some liberals became fixated on the legality of the election itself on account of accusations of Russian interference – a matter that will, initially at least, be settled in the courts. Yet more just became worn out. The daily barrage of venality, mendacity, tantrums and tweets has worn down many and turned off more.

Either way, at least where the electorate is concerned, America seems to have reached a new normal. Polls show that 38% of Americans think the country is moving in the right direction – that’s significantly higher than at this stage in both of Barack Obama’s terms. Trump’s approval ratings have climbed into the low 40s. That’s still low, but heading in the right direction. Republicans are intensely loyal to him – indeed, with the exception of George W Bush after 9/11, no other president has commanded this level of support from their party since the second world war.

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He is, it is true, loathed intensely too. Four of the five biggest marches in American history have taken place since his inauguration – none of them supported his agenda. But the certainty that this resistance would lead to a Democratic victory in November’s mid-terms is evaporating. Six months ago Democrats consistently held a double-digit advantage over Republicans in generic polling – over recent weeks their lead has been as low as one point.

It’s not difficult to fathom why this should be. While Trump is busy throwing all sorts of red meat to his supporters – steel tariffs, racial slights to footballers or sideswipes at the media – the Democrats have yet to formulate a coherent response to this moment beyond that they are not Trump. As the Rev Al Sharpton told Guardian journalists on Wednesday, waiting for Trump to self-destruct “is not a political strategy”.

Over the past week alone Trump has launched a trade war with his allies, held an Iftar dinner to mark the holy month of Ramadan, which Muslim groups boycotted, attacked his attorney general for recusing himself from the Russia investigation over a conflict of interest, disinvited Super Bowl winners the Philadelphia Eagles from a White House reception because he had heard several weren’t going to show up, and claimed he has the right to pardon himself. The remarkable thing about this week is that – compared with his behaviour in other weeks – it’s not that remarkable. The political situation in America is many things: it’s exhausting, exasperating, terrifying, volatile, vulgar, unsustainable and unhinged. The one thing it is not, is normal.

• Gary Younge is a Guardian columnist