President Donald Trump on Twitter is a bizarre, dangerous political figure who promotes a cult of the leader, using the tyranny of nationalism and state power to suffocate opposition. In person, rather than on social media, his behaviour is only lightly moderated. If you disagree, then you will get the phone slammed down on you. The president’s latest outpouring over the weekend was to attack a US district judge’s decision to temporarily halt his travel ban executive order. The White House statement called the ruling “outrageous”, before officials thought better of using such language.

Then there was Mr Trump’s “so-called judge” tweet – directed at someone appointed by George W Bush. Mr Trump’s legal officers appealed, claiming the court should not be “second-guessing” the executive. The message is clear and instantly recognisable to anyone who has followed events in post Brexit-referendum Britain: for populists who trade on nationalism, law does not matter, process does not matter; what does matter is a perpetual mobilisation against the “enemies of the people”. In Mr Trump’s case, identifying these foes is easy – just dip into his well of deep hatred for the elites: the scientists, the media and the judges who use facts and evidence to dispute his ludicrious empty-headed promises and blowhard rhetoric. In many ways Mr Trump is channelling his inner Richard Nixon, whose White House despised liberal elites tagging them an “effete core of impudent snobs”.

Previous presidents have seen their policies stymied by nationwide injunctions issued by federal courts – notably last year, when President Obama’s education department’s bathroom policy for transgender students was blocked. Presidents have also become exasperated with the supreme court. But it is a big jump from criticising a decision and attacking the authority of a sitting judge. If this continues, then the US would be taking a step into the unknown. In the US, the courts are an equal branch of government. One can differ in the correctness of a ruling, but to challenge the legitimacy of the court is fishing in dangerous waters. Mr Trump’s legal officers will be in the appeal court this week and there’s little doubt that the losers will take the case to the supreme court. Mr Trump’s eye for politics as performance art will no doubt spot a dramatic denouement to his signature campaign promise on the incendiary topic of immigration in the first 100 days of his presidency.

There is a wider concern here that Mr Trump’s antics are hastening a collapse of respect for established institutions. The news media have been under attack. Now it is the courts. Does the United States want to go from fake news to fake evidence? For a nation that is built on property rights and enforceable contracts, Mr Trump’s politics seem like an invitation to hold a grenade with the pin pulled out. There must also be an awareness of just how deeply Mr Trump might be willing to divide the US to deflect attention from his own policy failures, and how dangerous are the resentments he stirs. In fact, Mr Trump’s election looks not so much a populist reaction to liberalism, but as an exposure of the limits of both. Both are in search of legitimacy and refreshment.

There is an upside: the space opens up room for Mr Trump’s opponents to organise and criticise. It is hard to argue that Mr Trump’s politics have produced a new wave of solidarity. Every day in office Mr Trump widens divisions: between white and black, men and women, young and the old, military and political, judiciary and executive. The sense of dread is real – and it will not make America great again.