Suddenly, though, it has become apparent that the notion of Trump single-handedly changing American politics is far-fetched. Like other rabble-rousing outsiders of yesteryear hailed as paradigm-shifting saviours, he is about to find out he is mortal.

Rick Wilson, a veteran Florida political strategist close to both Jeb Bush, the Republican establishment favourite, and Marco Rubio, whom many party insiders increasingly view as a potential nominee, said Trump had been made to look like an “uninformed boob” in the debate.

“Carly Fiorina knocked him down on the appearance question,” he said, referring to her acid retort to his earlier comments about her face. Fiorina hit back: “I think women all over this country heard very clearly what Mr Trump said.”

Wilson said: “It was the first real blow any candidate in this race had landed on Donald Trump. Everyone on that stage realised he wasn’t invincible.

“He started to be bound by the normal rules of political gravity and physics and no longer got to just leverage his celebrity in terms of not having to play by the typical rules.”