The one welcome casualty of the coronavirus pandemic ought to be the culture wars. If it achieves nothing else, the health crisis has revealed the emptiness of leaders who manufacture nationalist fears to maintain their power. Boris Johnson now looks as out of place as a clown in a morgue. Donald Trump looks as out of luck as a cornered conman.

Nothing is inevitable, however. To see how a pandemic can be used to ensure that supplies of politically useful rage keep flowing, look at how US Republicans are constructing a cover story. They have plenty to cover up. The gaps in safety nets that the virus is revealing everywhere gape in the United States. That the world’s richest country somehow never got round to providing universal healthcare is bad enough, but the incompetence of Trump’s White House and the wider US right has been close to criminal.

“We have it under control. It’s going to be just fine,” Trump bragged on 22 January. He has never managed to rise from that low point. All Americans have had is bluff and bombast intended to make the virus seem a minor nuisance, and then, as reality dawned on the president’s narrow mind, to ensure blame went to anyone but himself. He was not alone. Fox News, which acts as a front for his administration and as the respectable face of crackpot politics, has been engaged in an equally clanking gearshift. At the beginning of March, liberal criticisms of Trump’s inability to see a national emergency when it was staring him in the face were “just another attempt to impeach the president”, according to one presenter. At worst, the virus “could be the flu”, added a second. Not even so bad a flu, opined a third. The U-turn in mid-March was so fast you could smell the burning rubber on the road. Overnight, coronavirus became a “health crisis” and an “incredibly dangerous and contagious virus”.

The honourable course, of admitting a mistake and expressing determination to do better, was unavailable

How do you recover from an error of such magnitude? The honourable course, of admitting a mistake and expressing a determination to do better in future, was unavailable – and not only because fighting in a culture war means never having to say you’re sorry. Honesty might be fatal to Trump’s hopes of re-election.

Instead, an escape attempt began with the right-wing deploying the language policing it so often deplores on the politically correct left. Trump is now insisting that coronavirus should not be called coronavirus but “Chinese virus”.

The side benefits he could expect to bank ought to be obvious. Trump could count on US liberals playing his game by accusing him of being an anti-Chinese racist. Liberals duly walked into the trap and Trump’s supporters were transported from the fear of living in an unprepared country with a demonstrably inadequate leader to the familiar ground of culture war. They could mutter: “Oh, these people call everything they don’t like racist; they’ll be saying it’s racist to call Chinese food ‘Chinese’ next.”

Trump could also count on the academically minded, saying scientists might once have named the coronavirus the “China virus” or “Wuhan virus” – as the Spanish flu and Ebola were named after the places where they were thought to originate. But the World Health Organization decided in 2015 that it wanted medically useful names. Trump’s supporters could shrug aside the WHO’s fancy talk and say that everyone knows the outbreak started because of China’s appalling treatment of animals, and the Chinese Communist party then added the suppression of news to its list of crimes by hiding the outbreak’s existence.

However much critics may want to say Trump is a semi-senile fool – and I do – it is worth remembering that he remains a brilliant political operator, who has destroyed all opponents within and without the Republican party who made the mistake of underestimating him. In this instance his cleverness, and the major benefit he expects to enjoy, lies in shifting the blame for his folly on to the Chinese.

If the virus is China's fault, then domestic critics of Trump's administration are traitors aiding Chinese communists

It does not stop there. If the virus is China’s fault, then domestic critics of his administration are traitors aiding the Chinese communists. You think I’m exaggerating? On 16 March, Trump tweeted a link to an article on the paranoid Federalist site. The author, one Madeline Osburn, was explicit. The Atlantic, a serious American magazine, had joined “China’s anti-American disinformation efforts”, she said. Osburn, who would have had a glittering career on the People’s Daily if she had been born Chinese, cited the work of The Atlantic’s Anne Applebaum, without appearing to know that Applebaum has written two devastating histories of the atrocities of communism. Describing how the pandemic has exposed America’s weaknesses in general, and its president’s weaknesses in particular, made Applebaum a useful idiot at best and traitor at worst, Osburn said.

The presidential retweet was not a one-off. By 19 March, Trump was saying in public that journalists who asked hard questions were “siding with China”. On 31 January, Trump had boasted: “We pretty much shut it down coming in from China. We have a tremendous relationship with China, which is a very positive thing.” By last week, he was counting on his supporters to have forgotten all that. This is how a failed presidency and failed political movement fights when it is in a corner.

The hope that events will justify your beliefs is an ineradicable delusion. Surely, now the British will see through Johnson, liberals say, rather than blindly rally to his government in a time of crisis. Surely, the Americans will toss Trump on the scrap heap in November. But political battles do not win themselves. Democrats still have to unseat a sitting president – a feat they have not managed since 1992. Labour still has to turn itself from a serial election-loser into an election-winning machine. As the US shows, coronavirus can become the “China virus”. And what seems an irrefutable argument for a comprehensive welfare state can become an excuse for nationalist tricksters to wrap themselves in their tattered flags.

• Nick Cohen is an Observer columnist