A week after Democrat Joe Biden clinched the election, Trump, a Republican, has refused to accept the outcome and has launched a flurry of dubious legal challenges to overturn the results. Election officials around the country have said they saw no evidence of serious irregularities.

Carrying flags and chanting "stop the steal", the protesters on Saturday walked from Freedom Plaza near the White House to the US Supreme Court building on Capitol Hill as part of the "Million MAGA March", referring to Trump's campaign mantra of "Make American Great Again".

Trump's motorcade briefly drove through the crowds on the way to his golf course in Sterling, Virginia. Demonstrators cheered as the president, wearing a red baseball cap emblazoned with the slogan, waved from inside the presidential limousine.

Donald Tarca Jr, who travelled to Washington from West Palm Beach, Florida, held a massive US flag sporting a giant portrait of Trump.

"I think it was rigged on multiple fronts," he said of the election. "Also, the media was so biased that they convinced millions of Americans to vote for Biden. They hate Trump."

Scores of members of the far-right Proud Boys group were among the marchers. Some left-wing groups staged small counter-demonstrations, including members of the loose movement known as antifa.

Near the Supreme Court, some counter-protesters carried black umbrellas and makeshift shields, while others formed a line of bicycles to prevent pro-Trump protesters from approaching their group from the rear. They called Trump supporters "Nazis"; the protesters shouted back a profanity about antifa.

Reuters witnessed at least half a dozen scuffles and several tense stand-offs in which police manned barricades between groups, but the violence appeared isolated.

In one instance, several counter-protesters near Union Station attacked a Trump supporter, who fell to the ground and received medical care after suffering a cut to the head.

The city's police department had made 10 arrests by midafternoon, a spokeswoman told Reuters, including four for firearms violations, two for assault and one for assaulting an officer.

The march was heavily promoted on social media, raising concerns it could spark conflict with anti-Trump demonstrators who have gathered near the White House in Black Lives Matter Plaza for weeks.

Smaller marches took place elsewhere in the US, including at Delray Beach, Florida, at the Capitol in Lansing, Michigan, and the Arizona Capitol in Phoenix.

Reuters with AP

Australian Associated Press