Whatever happens next, the Donald Trump effect will continue to stain politics the world over | Simon Tisdall

As Americans stared at their TV screens early on Thursday evening, listening to the 34 Donald Trump “guilty” court verdicts rolling out one by one amid the former president’s histrionic cries that the trial was “rigged”, the immediate thought was: what on earth happens now?

To which the only honest reply is: no one knows. Anyone pretending they do is just as big a liar as Trump, dramatically convicted by a jury of his New York peers for fiddling the books to help him win the 2016 election.

CNN’s Jake Tapper said the country and the world were witnessing “an unbelievable moment in American history”. But he quickly followed up with a health warning: “For those wondering about the political consequences… the short answer is nobody has any idea. Period.”

The phrase “uncharted territory” is already suffering serious overuse. Trump has signalled his intention to appeal. That process could stretch beyond election day on 5 November. Meanwhile, the convicted man remains at large. One of many ironies is that, as a citizen of Florida and now a felon, he may be banned from voting. It’s certain that Trump will attempt to weaponise the verdict, as he did the entire Manhattan prosecution, alleging a conspiracy to victimise him led by President Joe Biden and the Democrats. Trump falsely argued the process was politicised. Now he will personally guarantee that it is.

One obvious concern is that protests by angry Trump supporters could tip into violence as they adopt their leader’s “us versus them” stance. One flashpoint may be the Republican party’s nominating convention, taking place in Milwaukee only days after Trump is sentenced on 11 July.

“There is something very wrong here. We have gone over a cliff in America,” said Jeanine Pirro, a sympathetic Fox News host. The case was “riddled with errors” and partisan in nature, she claimed. “God help America after what I’ve seen in the last few weeks.”

Another linked question is whether Trump’s Make America Great Again fans will stay loyal. Analyst Frank Bruni noted a poll in early May found that 16% of Trump backers said they would reconsider their support if he were convicted; 4% said they would withdraw it.

But most Trump supporters will probably stick with their man, just as most Democrats will stick with Biden. A greater uncertainty surrounds the reaction to the first ever criminal conviction of a former or serving US president among independents and the uncommitted, especially young first-time voters.

Much of the electorate is basically immovable, Bruni suggested. “They’ve picked their tribe… and decided that whatever their leaders’ rough spots or rap sheets, the ideologues and crooks on the other side are worse… That’s part of why Trump probably is not finished.”

“Not finished” is last week’s parallel political verdict, and the world dare not ignore it. However much western allies, battered and bruised by Trump’s America First agenda during his 2017-2021 term, may hope to see the back of him, his influence and legacy – what might be called the “Trump effect” – will remain strong. Trump broadly embodies a range of developing, largely deplorable worldwide political trends. One of them, coarse incivility in public life, is a Trump trademark. It is spreading everywhere, often accompanied by physical violence. Trump’s non-ideological, personalised vilification of opponents and questioning of their motives places him at the cutting edge of a new era of disrespectful politics. Britain and other democracies are caught in a similar downward spiral. Ideas and policies are less debated. The focus is on discrediting, ridiculing and insulting opponents.

Trump used his trial to question the legitimacy and integrity of the entire US judicial system. Contempt for the law and the rules-based order, whether it’s the UN charter, international tribunals or national courts, is another expanding problem worldwide – which he gleefully feeds. Alleged war criminals such as Vladimir Putin and Benjamin Netanyahu rejoice in Trumpian legal iconoclasm and impunity. So, too, does every petty thief and crook trying to beat the rap.

Whether or not he wins in November, Trump’s intellectually incoherent, viscerally divisive populist-nationalist script will continue to find fans and emulators in authoritarian governments and among Europe’s far-right parties, set to make big gains in this week’s EU parliamentary elections. Like him, they know what they don’t like: migrants, establishment elites, globalisation, “woke” culture and environmentalists. And again like him, they have no answers to the problems they cynically exploit – but are here to stay.

And let’s not forget another Trump speciality with rising global appeal: disinformation and fake news – meaning lies. China, Russia and Iran all grow adept at disruptive online social media influence operations. They learn from the liar-in-chief. More worrying still for an international audience is the continuing impact of the “Trump effect” on geopolitics and the global balance of power. Even if Trump loses to Biden, says Hal Brands, a Johns Hopkins professor, his “America First” view of foreign and security policy will shape future US conduct and the world order ever more decisively in years to come. With Trump or without him, the US will continue to wield great power while increasingly shedding its global responsibilities, Brands argues. And it will grow less concerned about defending “distant allies” such as Ukraine, Taiwan and Nato.

The unending, unedifying age of Trump is one in which the US – no longer Madeleine Albright’s “indispensable nation”, no longer an exception – becomes in effect a normal country: self-interested, greedy, predatory, unreliable and increasingly authoritarian. If these characteristics sound familiar, they are. Trump seeks to refashion the US in his own image – and polls show he still has a big chance of succeeding. Far from making America great again, he would make it ordinary.

So, for everyone’s sake, lock him up!