The friendliest polling station I have visited was in Grozny, Chechnya. Separatist rebellion had been crushed by the Russian army, and a referendum was being held to confirm the republic’s loyalty to Moscow. Journalists were bussed in to witness democracy reborn amid the ruins of war. Officials were cheerful, as were our military minders. The Potemkin village atmosphere would have been festive but for an eerie lack of voters. Their shyness was not expressed in official results: 80% turnout; 96% in favour of a new pro-Kremlin constitution.

That episode, 14 years ago, was elementary ballot-rigging. The vote was in Russia’s backyard, overseen at gunpoint. Fiddling with elections in mature democracies thousands of miles away is harder. But no one with a critical eye on US politics doubts that Muscovite agencies stirred the pot in 2016, salting it with stolen emails, partisan Facebook ads and other meddlesome ingredients.

Quick Guide What you need to know about the Trump-Russia inquiry Show How serious are the allegations? The story of Donald Trump and Russia comes down to this: a sitting president or his campaign is suspected of having coordinated with a foreign country to manipulate a US election. The story could not be bigger, and the stakes for Trump – and the country – could not be higher. What are the key questions? Investigators are asking two basic questions: did Trump’s presidential campaign collude at any level with Russian operatives to sway the 2016 US presidential election? And did Trump or others break the law to throw investigators off the trail? What does the country think? While a majority of the American public now believes that Russia tried to disrupt the US election, opinions about Trump campaign involvement tend to split along partisan lines: 73% of Republicans, but only 13% of Democrats, believe Trump did “nothing wrong” in his dealings with Russia and its president, Vladimir Putin. What are the implications for Trump? The affair has the potential to eject Trump from office. Experienced legal observers believe that prosecutors are investigating whether Trump committed an obstruction of justice. Both Richard Nixon and Bill Clinton – the only presidents to face impeachment proceedings in the last century – were accused of obstruction of justice. But Trump’s fate is probably up to the voters. Even if strong evidence of wrongdoing by him or his cohort emerged, a Republican congressional majority would probably block any action to remove him from office. (Such an action would be a historical rarity.) What has happened so far? Former foreign policy adviser George Papadopolous pleaded guilty to perjury over his contacts with Russians linked to the Kremlin, and the president’s former campaign manager Paul Manafort and another aide face charges of money laundering. When will the inquiry come to an end? The investigations have an open timeline.

Establishing the scale of Russian support for Donald Trump’s candidacy is the job of special counsel Robert Mueller, a former FBI director. On Monday it was revealed that George Papadopoulos, an adviser to Trump’s campaign, has pleaded guilty to perjury, having lied about contacts with Russians claiming Kremlin ties. Separately, Trump’s former campaign manager Paul Manafort and one of his business cronies, Rick Gates, have been indicted for alleged money laundering, tax evasion and failure to disclose services to foreign powers. Those latter charges flow from “consultancy” work in Ukraine not directly linked to Trump’s presidential bid – a detail that the White House desperately depicts as a kind of exoneration. The logic is that consorting with suspected felons is fine, as long as the chronology doesn’t put smoke, gun and president all in the same room at the same time.

Comparisons with Watergate are inevitable but not very instructive. For one thing, the current allegations are way more serious. To collude with a foreign power in the subversion of democracy is treasonous. That was a line Richard Nixon didn’t cross. Nixon was also a different creature to Trump. He and his allies were eventually susceptible to shame. They did not want their wrongdoing exposed, but their cover-ups at least contained recognition that wrong and right might one day be judged by commonly accepted rules. Trump supporters understand political ethics differently: virtue is loyalty to the chief; truth is whatever he declares it to be. He cannot be shamed by a lie, because culpable “lying” can only occur in a space where there is respect for objectively verifiable facts.

There is no one within reach of power in the UK who touches Trumpian levels of malevolent narcissism, racist demagoguery and gross cupidity

Inability to accept that truth and justice operate independently from the person who wields power is the essence of Trump’s unfitness for office. It is what makes him not just intellectually incapable of doing the job, but morally hostile to American political tradition. Elections, parliaments and courts are the necessary apparatus of democracy. But, as I witnessed in Chechnya, they can be quickly assembled in flatpack form. Russia’s constitution promises political rights that have no bearing on Vladimir Putin’s governing methods. The 1936 Soviet constitution guaranteed elections and a free press. It did not inhibit Stalin’s atrocities.

Democracy can be enshrined in words but it thrives through an accumulated culture and habit of honouring those words. It is an ecosystem, like a coral reef that is marvellous not just because of its solid structures but because of the diverse flora and fauna they host – the competition for resources, the interaction of predator and prey, all sustained in delicate equilibrium.

Trump has not tampered much with the letter of the law, but his despotic temperament suffocates its spirit. The dishonesty, the cultivation of white supremacism, the legislative caprices, the verbal assaults on critics, plus the amplification of those tendencies by hyper-loyalists online, in Congress and in conservative media: it all poisons the water. No one knows at what point the reef loses its biodiversity, and democratic extinction begins.

As Mueller’s investigation unfolds, the White House will retreat to a defence of total executive privilege. Alongside diversionary tactics of lashing out at Democrats and the press, Trump’s team will act as if the president’s authority dwells beyond judicial investigations and congressional probes – as if he is above the law. In his mind, he is the law, able to bury Mueller’s findings and pardon the inculpated.

A tension has been brewing in the US between a type of politics that respects constitutional norms, and politics as a cult of personal power. That tension is about to erupt into full combat. If the Trumpians prevail, it will be catastrophic for liberal democracy. And not just in America. There is nothing original about the treatment of political institutions as weapons belonging to whoever has the means to snatch them and brandish them with ideological fervour. Nor is that desire exclusive to right or left. It animates nationalists and radical socialists alike.

Brexiters dislike Trump’s trade protectionism but were excited at the iconoclastic style of his victory. So too were some of Jeremy Corbyn’s firebrand supporters, even if they despise everything else about the US president. Revolutionary imaginations across the spectrum were stoked by the spectacle of raw willpower, populist zeal and organisational muscle upending conventional wisdom.

Mercifully, there is no one within reach of power in Britain who touches Trumpian levels of malevolent narcissism, racist demagoguery and gross cupidity. But we don’t have the luxury of presuming immunity from trends on the other side of the Atlantic, including interference by foreign powers. It is highly probable that Kremlin provocateurs are sprinkling spice into our politics, and not just through the official Russia Today propaganda TV channel.

That menace can be overstated. Foreign mischief does not extinguish a thriving democracy. It is dangerous only if it feeds a pattern of political climate change: the gradual pollution of the atmosphere by shameless lies and aggressive contempt for opposition; the loss of liberal oxygen that sustains a culture of tolerance, pluralism and respectful equilibrium between rival ideas. We do not know how far US democracy has gone down that path, how denuded that reef has become, how easily it can recover, and how far into our waters the contamination can spread. We will soon find out.