The Western democratic convention is one of adversarial politics. The principle is that the decisions of the party in power must be tested in parliament by opposition politicians. This can lead to absurdities whereby the automatic response of those not in power is to decry whatever the government does. But, by and large, it works.

For all the cutting invective, the limits of the adversarial principle are honored. Legislators are, after all, professionals. They know the rules. And once they have finished tearing strips off each other in the parliamentary chamber, they will often socialize quite happily and laugh about the debating points they have scored.

However, in America, adversarial politics has turned almost homicidal. Donald Trump is like no other US president. He does not play the Washington power games because he has never demonstrated anything but contempt for the American political establishment. On the campaign trail, he vowed to drain “the political swamp” on Capitol Hill. It was one of his most popular lines. US voters have been sickened by the partisan rivalries in Congress that have repeatedly brought the business of government to a grinding halt because bickering politicians would not agree on a budget.

Whatever anyone may think of Trump, he is the candidate whom most Americans chose. It does not matter that the result was a close-run thing. Had a relatively few more voters abstained or backed Hillary Clinton, America would now have its first female president. And had that been the case, victorious Democrats would have dismissed any Republican protests at the closeness of the outcome as sour grapes and told their rivals to get with the program.

But for the Democrat political establishment, what is sauce for the goose is clearly not sauce for the gander. Opposition to Trump is visceral. It is driven by hatred and far from being purely adversarial, is close to homicidal. Nothing this president can do escapes extreme condemnation.

The latest furor is over Trump’s “secret” second meeting with Putin at the G20 in Hamburg. Well no, actually, the two world leaders were at a private dinner. There was nothing secret about it. And even Democrats talk at dinner parties, don’t they? But then the Trump-haters found a new act of presidential evil. There had only been one interpreter between Trump and Putin and he had been a Russian. Normally leaders have their own interpreter. This hokum of course plays to the Democrat line that Trump is a “Manchurian candidate”, groomed by the Kremlin and helped to power by Russian hackers and dirty tricks.

What America’s liberal establishment is actually doing in this relentless assault on every single thing Trump does is seriously endangering the whole US political process. The deal used to be that whatever you thought about the president himself, you showed respect for the office of president. George W. Bush scraped a victory thanks to some dubious electronic voting but rival Al Gore wisely pulled back from challenging the results in the courts. Instead, he rallied around the presidency, rather than the man who had won it. By today destroying respect for the office of presidency, the Democrats will surely pay a bitter price when tomorrow another of their number occupies the Oval Office.