Harris’ spokesperson Sabrina Singh called the moment “incredibly racist”.

John Burke, communications director for Perdue’s campaign, insisted the senator “simply mispronounced” her name “didn’t mean anything by it”.

“He was making an argument against the radical socialist agenda that she and her endorsed candidate Jon Ossoff are pushing, which includes the Green New Deal, Medicare-for-all, raising taxes, and holding up Covid relief for the people of Georgia,” Burke concluded.

Casey Black, a spokesperson for Perdue’s campaign, maintained that the senator “simply mispronounced Senator Harris’ name”.

In response, Singh said they must “do better”.

Andrew Bates, a spokesman for Biden’s campaign, tweeted: “My entire life, I’ve HATED dehumanising, cynical displays like this that spread vile, racist poison and insult the dignity of the South – especially when they’re obviously calculated. As a country & a region, we are so much better than David Perdue.”

The non-partisan Cook Political Report ranks the Georgia seat as a toss-up between Perdue and Ossoff, while RealClearPolitics shows Perdue to be about one point ahead, per their polling average.

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Ossoff wrote that “Senator Perdue never would have done this to a male colleague. Or a white colleague. And everyone knows it.”

He also tweeted “we are so much better than this” in sharing a clip Perdue mispronouncing Harris’ name.

In an appearance on MSNBC, Ossoff said, “This kind of vile, race-baiting trash talk is what President Trump has unleashed from sitting Republican members in the Senate.”

Trump has repeatedly, purposely and mockingly, mispronounced the California senator’s first name.

Harris, the daughter of Jamaican and Indian immigrants, is the first black woman and Asian person on a major party’s presidential ticket.

“Senator David Perdue has served in the Senate alongside Vice-Presidential nominee and Senator Kamala Harris since 2017,” the Democratic Senatorial Campaign Committee said in a statement.

“He knows her name and he knows how to say it. His disgusting performance today is nothing more than a desperate dog whistle from a losing politician who was already caught running anti-Semitic ads against Jon Ossoff. Perdue has shown he lacks the dignity and respect that Georgians deserve from their US senator, and he must immediately apologise.”

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Representative Ted Lieu, D-Calif., posted, “We all watched the video. You didn’t simply mispronounce your colleague’s name. You mocked” Harris’s name and he should “at least have the courage to own up to it.”

Meena Harris, the VP nominee’s niece, tweeted, “Let’s call him what he is: racist.”

Trump campaigned on Friday in Florida and Georgia, neighbouring states he carried four years ago and must win again to extend his presidency. His decision to devote Friday evening’s prime-time slot to Georgia in particular highlighted the serious nature of his challenge: Far from his original plan to expand into Democratic-leaning states, he is labouring to stave off a defeat of major proportions.

In Florida, the president derided the Bidens as “an organised crime family”, renewing his daily claims about the candidate’s son, Hunter, and his business dealings in Ukraine and China.

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More to the point for Trump’s Florida audience, he spoke directly to seniors who have increasingly soured on his handling of the pandemic.

“I am moving heaven and earth to safeguard our seniors from the China virus,” Trump said, using his usual blame-shifting term to describe the coronavirus. He also offered an optimistic assessment of the pandemic, even as a surge of new infections spreads across America.

“We are prevailing,” the president said, promising to deliver the first doses of a vaccine to seniors when it’s ready.

It was just the opposite as Biden opened his Michigan swing at a suburban Detroit community centre. In keeping with his usual protocols, Biden and all the participants wore masks throughout the event, except when they were speaking, and a small crowd of dozens of reporters and supporters watched from folding chairs separated by circles to ensure social distancing.

“He’s living in a dream world,” Biden said of Trump’s rosy predictions of the pandemic. The former vice-president then turned to the Trump administration’s court fight to overturn the “Obamacare” health coverage law – including its protection for people with pre-existing conditions – without having a replacement plan.

“Mishandling the pandemic isn’t enough for Trump,” Biden charged. “On top of that he’s still trying to take away your health care.”

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Meanwhile, the president’s campaign released new numbers suggesting he’s likely the first incumbent president to face a fundraising disadvantage in the modern era.

Trump’s campaign, along with the Republican National Committee and associated groups, raised US$247.8 million in September, well short of the US$383 million raised by Biden and the Democratic National Committee. To open October, the Trump effort officially had US$251.4 million in the bank, according to a campaign spokesman, compared with US$432 million for Biden.

Trump claimed he could have raised more. He said he could call the heads of Wall Street firms and ask for millions, but added: “I can’t do that though, because you know what, if I do that, I got to do things for them. I could be the world’s greatest fundraiser, but I just don’t want to do it.”