US President Trump tells supporters he will lead a march on Congress as lawmakers prepare to count electoral college votes to certify Joe Biden's victory in November's presidential election.

US President Trump speaks to supporters from The Ellipse near the White House on January 6, 2021, in Washington, DC.
US President Trump speaks to supporters from The Ellipse near the White House on January 6, 2021, in Washington, DC. (AFP)

President Donald Trump has told a rally of his supporters outside the White House that he will never concede that he lost the election, as Congress readied to certify Joe Biden's victory.

"We will never give up. We will never concede," Trump told the cheering crowd on Wednesday. "We will stop the steal."

"We won 75 million votes and they say we lost; we didn't lose... We don't want to see our election victory stolen by emboldened, radical Democrats," Trump said. 

He also urged his deputy Mike Pence not to certify Biden's election victory at a Congress session starting later in the day, repeating unfounded allegations of vote fraud.

"If Mike Pence does the right thing, we win the election. He has the absolute right to do it.

"Mike Pence is going to have to come through for us, and if he doesn't, that will be a sad day for our country."

Trump rebuked "weak" Republicans planning to go along with the certification, accusing them of having "turned a blind eye" and threatening them with primary challenges in future elections. 

Congress due to certify Biden's victory

Thousands of his supporters including members of far-right groups have gathered in Washington, DC in protest at a meeting of Congress to certify Biden's victory in November's presidential election.

Earlier, one of his sons, Eric Trump, warmed up the flag-waving crowds with unfounded conspiracy theories.

"Is there any person here that actually thinks that Joe Biden won this election?" Eric Trump said to shouts of "No."

The states have all certified that Biden, a Democrat, won the election by 306 electoral college votes to Trump's 232, and Trump's challenges to Biden's victory have floundered in courts across the country.

"It doesn't matter," Eric Trump said. 

"They can lie; they can cheat; they can steal. My father has started a movement and this movement will never, ever die."

Congress was due to certify Biden's victory on Wednesday. 

Many of Trump's fellow Republicans have promised a stonewalling effort that could stretch proceedings past midnight but was almost certain to fail.

Washington police earlier banned from the city Enrique Tarrio, the leader of the Trump-supporting far-right group the Proud Boys, after he was arrested on Monday for the destruction of property and possession of a firearm magazine. 

Tarrio could not immediately be reached for comment.

READ MORE: Trump loyalists rally in Washington refusing to accept election results

Protesters told to shun guns

Crowd control largely fell to the Metropolitan Police Department, which mobilized all 3,750 officers, the Capitol Police, the Park Police, the US Secret Service, and more than 300 members of the city’s National Guard, according to Washington police chief Robert Contee and other officials.

Police have told protesters not to bring their guns to Washington, which has some of the nation's strictest gun laws and bans the open carrying of firearms.

On Tuesday evening, Trump supporters trying to reach Black Lives Matter Plaza in Washington were stopped by riot gear-clad police, who used pepper spray and batons to drive them back.

"I’m just here to support the president," said David Wideman, a 45-year-old firefighter who travelled from Memphis, Tennessee. 

Wideman acknowledged he was "confused" by a string of losses from Trump’s legal team in their attempt to overturn the results of the election and didn’t know what options Trump had left.

"I not sure what he can do at this point, but I want to hear what he has to say," Wideman said.

READ MORE: Georgia run-offs: Millions vote in US state with Senate at stake

Biden hopeful Democrats will have Senate majority

Also on Wednesday, President-elect Joe Biden said he was hopeful Jon Ossoff would be victorious after fellow Democrat Raphael Warnock was projected to win one of the two US Senate seats up for grabs in Tuesday's run-off elections.

Biden in a statement promised to work with both parties to address the Covid-19 pandemic and move forward his cabinet nominations, adding it looked like Georgia's voters had given Democrats a majority in the US Senate.

READ MORE: Leader of neo-fascist Proud Boys arrested ahead of pro-Trump rallies

Source: TRTWorld and agencies