A supporter of US President Donald Trump (left) is attacked by anti-Trump demonstrators in Black Lives Matter Plaza in Washington DC on Saturday. Photo: AFP

Thousands of die-hard Donald Trump supporters rallied for a last stand Saturday in Washington DC, chanting "four more years" and blaming fraud for an election defeat that will force the president to vacate the White House after just one term.

Trump himself made a drive-past in his armored motorcade, on his way to play golf, smiling through his limousine window to wild cheers and signs saying "Best prez ever" and "Trump 2020: Keep America Great."

"We wanted to show our support, we're feeling they are trying to steal the election," said Pam Ross, who drove eight hours from Ohio to join the rally, referring to the president's political opponents.

The Republican incumbent is sticking to discredited claims of mass fraud and claiming he defeated president-elect Joe Biden in the November 3 vote, marking another unprecedented challenge to US democratic norms as his time in office runs down.

Later Saturday, he took to Twitter with a series of tweets and retweets that included claims of voting machines potentially being hacked and complaints about news networks' coverage of the rally.

Twitter slapped labels on at least eight of the posts as containing "disputed" information.

At least 10,000 people - few wearing masks - massed on the city's Freedom Plaza before marching to the Supreme Court in a raucous atmosphere reminiscent of a Trump campaign rally.

"President Trump deserves to see who's behind him, he deserves to feel the love," Kris Napolitana, from Baltimore, told AFP. "I believe that he's going to win when all the fraud and cheating is found out."

With right-wing militia group, the Proud Boys among those attending, a large security presence was deployed to prevent clashes with anti-Trump events outside the Supreme Court.

Groups of counter-protesters stood nearby, some yelling about social justice and Trump supporters not wearing masks.

There were a number of scuffles, but no major violence had been reported.

As night fell, police formed lines on either side of a street leading to the White House, separating hundreds of rival protesters.

AFP