Trump fumed and his face turned red. Then the debate got weird.

With a well-placed jab about his rally size, Harris derailed any hope that Trump could act normally, Richard Hall writes in an analysis of Tuesday’s debate in Philadelphia

Kamala Harris laid the bait for Donald Trump by attacking the most precious thing to him in the world - his rallies.

“He talks about fictional characters like Hannibal Lecter. He will talk about how windmills cause cancer. What you will also notice is that people start leaving his rallies early out of exhaustion and boredom. The one thing you will not hear him talk about is you,” she said, in a moment that was likely rehearsed for days.

Trump’s eyes widened and his face dropped. He could no longer hear the moderators above the ringing in his ears.

“Let me respond just to the rallies,” he said, ignoring a question about the border. “People don’t leave my rallies. We have the biggest rallies, the most incredible rallies in the history of politics,” he went on.

The man who has spent every debate of his life burrowing beneath the skin of his opponents was finally on the receiving end of it.

From that moment on, his voice rarely fell below a shout. His sentences were disjointed. His syntax was confused. His face was red. His brow was furrowed. He leaned forward towards the empty space in front of him.

The worst was still yet to come.

Republican presidential nominee former President Donald Trump speaks during a presidential debate with Democratic presidential nominee Vice President Kamala Harris. (AP)

In perhaps the strangest moment of the debate, or of any presidential debate in US history, Trump stumbled from a defense of his rallies to the sharing of an online conspiracy theory about Haitian migrants eating cats in Springfield, Ohio.

“In Springfield, they’re eating the dogs — the people that came in — they are eating the cats. They’re eating … they’re eating the pets of the people that live there,” he said.

When the moderator, ABC’s David Muir, said there had been no credible reports of pets being harmed, the former president responded with an answer that might have prompted a wellness check if it had been uttered anywhere but the debate stage: “The people on television say my dog was taken and used for food.”

The split-screen was not kind to Trump. As he summoned images of dead cats from his imagination, Harris’s facial expressions told a story all of their own. She laughed and winced through his answers.

This was not the imposing Trump that stalked Hillary Clinton in 2016. Or the restrained Trump that spoke quietly as Joe Biden stumbled just two and a half months ago.

Trump’s debate style was once compared to a “malfunctioning appliance.” On stage this evening, he resembled a whistling kettle rattling on a stove. He never found his footing.

Harris baited him again and again, attacking his temperament, calling him weak and a “disgrace”. She stared straight at Trump as she told him world leaders were “laughing at Donald Trump,” and called him “confused about fact.”

Harris listens to Trump during the debate. She threw him off his game by just bringing up his rallies. (AP)

Trump fixed his gaze square ahead. His anger at an invisible mark in front of his lectern only grew.

“Let me just tell you about world leaders. Viktor Orban, one of the most respected men -- they call him a strong man. He’s a tough person. Smart. Prime Minister of Hungary. They said why is the whole world blowing up? Three years ago it wasn’t. Why is it blowing up? He said because you need Trump back as president,” he said, before listing more dictators who thought he was a good guy.

Harris landed her biggest punches on Trump on abortion and race.

In what is likely to be her most viral moment, she was able to deliver a powerful rebuke of Trump’s dismantling of Roe v Wade.

“Trump abortion bans that make no exception even for rape and incest. Understand what that means. A survivor of a crime, a violation of their body, does not have the right to make a decision about what happens to their body next. That is immoral,” she said.

“And one does not have to abandon their faith or deeply held beliefs to agree the government, and Donald Trump certainly, should not be telling a woman what to do with her body,” she added.

Trump, meanwhile, prevaricated on his position on a national abortion ban and made the absurd claim that Harris’s running-mate, Tim Walz, supports “execution after birth.”

That prompted a sullen moderator, Linsey Davis, to remind the former president: “There is no state in this country where it is legal to kill a baby after it’s born.”

Trump lost his cool, then spouted false claims and continued to hit the same talking points from the campaign trail, offering little new. (REUTERS/REUTERS)

Trump had hoped to use the debate to tie Harris to all of Biden’s failures. By the end, Harris had more success prosecuting the case against Trump.

In her closing statement, Harris spoke of the candidates’ “two very different visions for our country.”

“One that is focused on the future and the other that is focused on the past. And an attempt to take us backward. But we’re not going back. And I do believe that the American people know we all have so much more in common than what separates us and we can chart a new way forward,” she said.

Trump ended with a question for Harris.

“So, she just started by saying she’s going to do this, she’s going to do that, she’s going to do all these wonderful things. Why hasn’t she done it?” he asked.

“We’re a failing nation. We’re a nation that’s in serious decline. We’re being laughed at all over the world. All over the world, they laugh, I know the leaders very well. They’re coming to see me. They call me. We’re laughed at all over the world. They don’t understand what happened to us as a nation. We’re not a leader. We don’t have any idea what’s going on,” he added.

As he walked off stage, Donald Trump must have been wishing he had gone easier on Joe Biden.

Make sense of the US election with The Independent’s experts in our exclusive virtual event ‘Harris vs. Trump: who will make history?’ Reserve your space here.