Donald Trump has called his election opponent, Kamala Harris, “mentally disabled” in the latest escalation of his rhetoric against her.

“Joe Biden became mentally impaired. Kamala was born that way,” Mr Trump told his supporters during a rally in the swing state Wisconsin today.

“She was born that way. And if you think about it, only a mentally disabled person could have allowed this to happen to our country. Anybody would know this.”

The shot at Ms Harris’s intelligence lines up with Mr Trump’s previous, repeated claims that the Vice President is a “low IQ individual”.

Ms Harris took over from Mr Biden as the Democratic Party’s presidential candidate in late July after concerns about his age and mental acuity led his own party to force him out of the race. She will face Mr Trump, the Republican nominee, in the election on November 5.

“I can’t even believe she’s being considered,” Mr Trump said today.

“She was considered, eight weeks ago, the worst vice president in history. A very dumb person. The fake news was calling her ‘dumb’, ‘stupid’, ‘didn’t have a chance’.”

Before she became Vice President in 2021, Ms Harris was a prosecutor, the district-attorney of San Francisco, the attorney-general of California and then a US senator.

If she wins in November she will become the country’s first female president.

Much of Mr Trump’s speech in Wisconsin focused on immigration. He blamed Ms Harris for the passage of undocumented migrants across America’s border with Mexico.

To drive home that message, he spoke in front of a backdrop which featured the slogans “End Migrant Crime” and “Deport Illegals Now”.

“Look, you’ve got to do what you’ve got to do. You’ve got to get these people back where they came from. You have no choice. You’re going to lose your culture,” Mr Trump said.

Mr Trump has promised to deport undocumented migrants on an unprecedented scale, should he return to the presidency in January, though he has yet to specify how any such deportation program would work, given the sheer numbers involved.

There are thought to be about 12 million undocumented migrants living in the United States, with some estimates going as high as 20 million. Rounding them up, and removing them from the country, would require an immense, highly co-ordinated operation from the government, as well as co-operation from their countries of origin.

In the weeks since his debate against Ms Harris, Mr Trump and his nominee for vice president, Senator J.D. Vance, have largely focused their fire on a community of Haitian immigrants living in the city Springfield, Ohio.

The Republican candidates initially seized on thin rumours that the migrants had been killing and eating people’s pets.

“They’re eating the dogs, the people that came in. They’re eating the cats. They’re eating the pets of the people that live there. This is what’s happening in our country, and it is a shame,” Mr Trump claimed during that debate.

There is still no actual evidence for that allegation.

The woman whose Facebook post was picked up by right-wing figures on social media, causing the pet-eating rumour to go viral and, apparently, grab the former president’s attention, has since clarified that her cat – which she initially thought had been stolen by migrants – was found alive and well in her own basement.

She says she regrets her initial post.

Mr Vance, in particular, also claims the Haitians’ arrival in Springfield has coincided with a “massive rise” in communicable diseases. Official data shows that disease rates have, in fact, fallen during the relevant time period.

We should note that the Haitians living in Springfield are not illegal immigrants; they are in the country legally.