IT will be the first US presidential debate on Monday but, apparently, Donald Trump isn’t sweating it. While Hillary Clinton has been closeted away prepping for the big match, Mr Trump is apparently intending to wing it.

Is that good? Does it mean his epic hubris will finally get the better of him? He may be used to sealing deals by drawing himself to his full height (6ft 3in including quiff) and imposing the force of his massive unfettered will but, in the forensic forum of the TV debate, his loose relationship with fact and detail will be his undoing. Surely.

If only. His clubhouse, loudmouth persona, we can see all too clearly by now, is exactly what is keeping him in the race. Sticking to the facts, tempering your language to reflect the complexity of the issues – that is what political insiders do while pub blowhards call for huge walls to keep out immigrants. The last thing this presidential candidate wants is to be mistaken for a politician.

Xenophobic policy pronouncements, conspiracy theories, exaggeration and falsehood have served Mr Trump well so far. After years of casting doubt about whether President Obama was born in the United States, he reversed the stance without a hint of apology as recently as last week, actually trying to claim the moral high ground by asserting that Mrs Clinton’s campaign in 2008 had started the rumour, which is completely false as many news networks and fact checking sites have confirmed.

He claims he opposed the Iraq war when he is on record as having supported it; he says that he started his multibillion-pound business with a “small loan” (in fact, it was for $1 million from his father Fred Trump who, the Washington Post has pointed out, was a silent partner in his first big deal, providing backing worth many millions more). The list goes on. When politicians stop caring about nuance and truth and connect with voters with casual populism and off-the-cuff assertions, all bets are off. Monday will be tough for Mrs Clinton.

You might expect it to be harder to get away with this stuff in the social media age, when every politician’s remark is subjected to such scrutiny. Twitter users and online commentators promptly home in on falsehoods.

But in cyberspace no one can hear you reason. The hysterical, the ignorant and the stupid have equal billing with those who try to find evidence to back up their point of view. There is no referee, in short, and that can only benefit those who peddle glib and fact-lite politics.

So it is no surprise that Mr Trump has made it known he doesn’t want the moderators of the TV presidential debates to correct untruths uttered by the candidates.

He must know that effective fact-checking would harm him, not his opponent. As an establishment figure and veteran politician, Mrs Clinton has struggled to hold the trust of voters. The last thing Mr Trump wants is a TV-debate anchor who points out where he’s wrong, while Mrs Clinton stays on the right side of the truth. It would hardly play to the right narrative. Better for Mr Trump that he gets another moderator like CNN’s Matt Lauer, who interviewed him on national security issues recently and failed to challenge his claim to have opposed the Iraq invasion.

This has been called, infamously, the age of ignorance, a post-factual era in which evidence and truth are regarded by some as elitist.

Remember that Leave campaign claim that the NHS would receive £350m a week in the event of Brexit? It was a porky pie the size of Melton Mowbray, but Leavers unrepentantly stuck with it until after the EU vote – only two hours after in Nigel Farage’s case (he disowned it on breakfast TV) – but long enough for it to have hoodwinked enough voters to win the day. Consequences? There has been none. The inevitable reversal has barely occasioned any comment. It is all far too late.

But it doesn’t have to be like this and journalists have to be on the frontline of reasserting meaningful standards. No wonder Mrs Clinton is practising her lines. Her experience to date has been that she has faced tougher questioning from journalists than from Mr Trump. If Monday’s moderator, Lester Holt, shies away from challenging Mr Trump if he errs from the truth, the scene will be set for a walkover by the combover.

The moderators might fear accusations of political bias but it can never be biased to challenge exaggeration or falsehood. Mr Trump might look like he’s playing at politics but this is no game. If he doesn’t think the detail matters, then perhaps Monday would be a good time for him to learn otherwise.