Kamala Harris has told tens of thousands of people in Washington that her opponent Donald Trump is seeking unchecked power as US president as the campaign for the White House enters its final week.

Harris spoke to an outdoor crowd estimated by her campaign of more than 75,000 people at the site near the White House where on January 6, 2021, Trump addressed his supporters before they attacked the US Capitol.

“We know who Donald Trump is,” Harris said, adding the former president “sent an armed mob” to the US Capitol to try to overturn the results of the 2020 election.

“This is someone who is unstable, obsessed with revenge, consumed with grievance and out for unchecked power,” Harris said during her campaign’s closing argument before next Tuesday’s tightly contested US presidential election.

Harris was flanked by American flags on stage and surrounded by blue and white banners that said “Freedom” with the lit-up White House in the background.

“One week from today, you will have the chance to make a decision that directly impacts your life, the life of your family and the future of this country we love,” she said.

“It is a choice about whether we have a country rooted in freedom for every American, or ruled by chaos and division.”

She encouraged the crowd and voters to move on from the Trump political era – and finished her speech by calling him a “petty tyrant”.

“The United States of America is not a vessel for the schemes of wannabe dictators. The United States of America is the greatest idea humanity ever devised,” she said.

A Reuters/Ipsos poll on Tuesday showed that Harris’s lead had eroded to just 44 per cent to 43 per cent among registered voters.

Harris has led Trump in every Reuters/Ipsos poll since she entered the race in July, but her advantage has steadily shrunk since late September.

Trump and his allies have sought to play down the violence of January 6.

Thousands of his supporters stormed the Capitol, sending lawmakers fleeing for their lives and chanting “Hang Mike Pence” the then-vice president, after Trump’s address on the Ellipse, where as president he told the crowd to “fight like hell” to prevent Pence and Congress from ratifying his loss.

Four people died in the ensuing riot at the Capitol, and one police officer who defended the Capitol died the following day.

Trump has said that if re-elected, he would pardon the more than 1500 participants who have been charged with crimes.

Earlier in Florida, the Republican campaign tried to move on from racist and other vulgar remarks by speakers at Trump’s rally in New York City on Sunday. Trump defended the event “an absolute love fest.”

Trump did not comment on the rhetoric used by speakers at the event, where a comedian called Puerto Rico a “floating island of garbage” and disparaged black Americans, Jewish people, Palestinians and Latinos.

Though his campaign has said the comments about Puerto Rico did not reflect his views, Trump called the event a love fest.

“It was my honour to be involved,” he said.

Some 51 million Americans have already voted in the election, according to Election Hub at the University of Florida, in a battle that will decide who runs the world’s richest and most powerful country for four years.

Trump has said Harris is too dangerous to serve as president, pointing to foreign wars and high levels of immigration while she has been vice president. He said she had waged a campaign of destruction.

“But really, more than anything else it’s a campaign of hate,” he said.

Both candidates are seeking to cement voters’ opinions in the final days of a historically close election.

Trump aims to capitalise on voters’ unhappiness with rising prices and immigration, while Harris has emphasised abortion rights and has described Trump as an aspiring dictator who would undermine US democracy.

Trump was later to visit a heavily Hispanic city in Pennsylvania, two days after comedian Tony Hinchcliffe’s comments about Puerto Rico drew outrage at the New York rally.

Puerto Ricans are the largest Hispanic group in Pennsylvania, the most crucial battleground state to win as it holds the highest number of Electoral College votes of the septet, according to the Census Bureau.

-with AAP