US President Donald Trump faces moderator Chris Wallace. (Image: C-Span)

There is an almost impossible problem with assessing how US President Donald Trump performs in any debate, or in any public forum really. There is simply a different rulebook — if there is a rulebook — applied to him.

So it went with the ill-tempered and rambling first presidential debate, moderated by Fox News’ Chris Wallace at a university hospital in Cleveland, Ohio.

Because of course, Trump’s reality TV nastiness, his shamelessness, his personal attacks are all kind of the point — the sense that he in some way shows up the hypocrisy and false civility of the establishment is possibly the most coherent content he has.

So while Joe Biden’s minders would have been fretting over whether he’d use archaic racial slang to describe Puerto Ricans, or call someone’s five-year-old “a real looker”, Trump would be called “presidential” or at least “uncharacteristically sedate” if he didn’t accuse Biden of being involved in the attempted assassination of Ronald Reagan.

Those lowered standards work straightaway; he answers the first question (about the Supreme Court) without any demonstrable lies or slurs — and I’m impressed.

That lasts until Biden starts talking, and the two start bickering about healthcare policy. By question two, Trump won’t let Wallace finish a question (“Oh, I guess I’m not debating him, I’m debating you now, but that’s not a surprise”).

Things go off the rails at this point, and barely get back on them.

This was also our first chance to really see what Trump would do when campaigning against a man. He didn’t loom like a predatory toad over Biden’s shoulder as he did with Hillary Clinton four years ago, but he probably interrupted and taunted him more. Wallace had to literally beg him to stop. Which he did, for one question.

Can we imagine his performance tonight swing a single vote his way? Hell, if anything the debate just served to reinforce the absurdity of an undecided voter in September 2020.

Trump came into this debate with, as ever, three or four scandals — career killers for any previous president — over his head. So, just as it was four years ago, when he looked likely to lose, he appears to think his best bet is twofold: wearying personal attacks on his opponents, and conspiratorial attacks on the legitimacy of the process.

So to the personal: mostly it was his attacks on Biden’s son Hunter, accused of various shady dealing but most frequently of taking US$3.5 million from the mayor of Moscow. Trump keeps saying it, and saying it, and saying it as Biden tries to answer other questions, clearly trying to goad Biden into an embarrassing reaction. This is the one time Biden’s somnambulant performance really played in his favour, and he kept his cool.

There were all the classics for Trump watchers. Those verbal tics, sweeping statements that rely heavily on allusion (“If you see what’s happening in Virginia, it’s really terrible”) and everything he’s done is immaculate, phenomenal, the “most” something you’ve ever seen. He often talks like a child writing dialogue for a fictional president: “I talked to the scientists in charge and they say they’ll have a vaccine.”

There was the repetition of specific but baseless accusations — in this case that there would be 2 million dead of COVID-19 had Biden been president. He once again refused to condemn white supremacists (“It’s not a right-wing problem it’s a left-wing problem”).

More broadly, he wants to de-legitimse the process, once again refusing to confirm that he’d make a peaceful transfer of power (“If I see tens of thousands of ballots being interfered with it, then I don’t go along”), continually launching into rambling accusations of fraud and corruption compromising mail-in ballots.

None of which is surprising, except when you stop to think about it for a second, to take it all as a totality: Trump geeing up the violent elements of his support, telling them not accept the election result if he loses.

As part of his mail fraud rant he said something that made me slightly queasy. He said it a few times: “This is not going to end well.”