ATLANTA, United States (AFP) — Kamala Harris accused Donald Trump of stoking divisions in the final week of a tight White House race Monday after comments made by speakers at the Republican’s weekend mega-rally were widely condemned as racist.

As they entered the final week of one of the closest US presidential elections in history, Democrat Harris crisscrossed Michigan while Republican Trump headed to Georgia, another of the decisive swing states.

More than 44 million Americans have already cast ballots in early voting — including outgoing Democratic President Joe Biden, who voted on Monday after waiting in a long line near his hometown of Wilmington, Delaware.

Tensions are soaring in a race that polls suggest is too close to call, fuelled by fears that former president Trump could again refuse to recognise a defeat, as he did in 2020, and by his harsh rhetoric threatening migrants and political opponents.

Concerns increased after a fire reportedly consumed hundreds of early ballots cast in a supposedly secure drop-off box in a highly competitive district in northwestern Washington state. Arson was reportedly suspected in another ballot box fire hours earlier in Portland, Oregon.

And Trump has faced renewed outrage after one of the warm-up speakers at his huge Sunday rally in New York’s Madison Square Garden called Puerto Rico “a floating island of garbage”.

“Last night, Donald Trump’s event in Madison Square Garden really highlighted a point that I’ve been making throughout this campaign,” Harris told reporters as she headed for Michigan on Air Force Two.

“He is focused and actually fixated on his grievances, on himself, and on dividing our country. And it is not in any way something that will strengthen the American family, the American worker.”

The former president’s campaign said the comments on Puerto Rico did “not reflect the views of President Trump”.

Residents in the US territory cannot vote in presidential elections, but those within the United States proper — which includes about 450,000 Puerto Ricans in the crucial battleground state of Pennsylvania — can.

However, the speaker, comedian Tony Hinchcliffe, was unrepentant, writing on social media that critics “have no sense of humour” — a comment reposted by Trump’s son and advisor Don Trump Jr.

Hinchcliffe also mocked a black man by referring to a watermelon — a deep-rooted racist stereotype in the United States — and made fun of Latinos’ birth control.

Other speakers used openly sexist and racist rhetoric to mock Harris sexually and called her the “anti-Christ”.

Trump, meanwhile, used the event — likened by Democrats to an infamous 1939 rally of American fascists in the same venue — to lash out on familiar topics including undocumented migrants and domestic opponents whom he again branded the “enemy from within”.

As the clock ticks down, the challenge for Harris and Trump is both to energise core supporters and pull in the tiny number of persuadable voters who might still tip the balance — especially in the seven swing states where polls suggest they are running neck-and-neck.

Harris, who spent Sunday in must-win Pennsylvania, was holding three events in Michigan, while Trump was to hold two in Georgia — a pattern set to be repeated around the country’s other battlegrounds for the next seven days.