Donald Trump supporters rallied in Washington on Saturday to push the discredited theory that fraud denied him rightful victory in the election, though turnout for the protest was uncertain as further results cemented the president's defeat.

Trump expressed his thanks and suggested he might "stop by and say hello" at rallies held under the banners of "Stop The Steal," "Million MAGA March" and "Women for America First."

Right-wing militia groups such as the Proud Boys also planned to hold rallies, prompting a large security presence in the capital to prevent clashes with separate anti-Trump events that were scheduled outside the Supreme Court.

"The whole system's rigged... in the way that the information is getting to the people, it's filtered through these channels that makes it so that the truth never actually gets out," said marcher Darion Schaublin, 26, who drove to Washington from Columbus, Ohio. "There is a good chance... he is not going to have a second term -- and I'm not sure of the legitimacy of that."

The final two undeclared states were called on Friday by US television networks -- with Democrat challenger Joe Biden winning the former Republican stronghold of Georgia in an extremely close race, and Trump getting North Carolina.

The latest tallies gave Biden a solid overall final win in the state-by-state Electoral College that decides the presidency, with 306 votes against Trump's 232. Two hundred seventy votes are required for election.

President Trump continues to impede Biden's ability to prepare for his transition ahead of inauguration on January 20 and has filed numerous lawsuits -- so far unsuccessfully -- to challenge vote counts around the country.

On Friday, a judge in Michigan issued another rejection of Republican claims of fraud.

'Time will tell'

Trump said Friday that "time will tell" if he remains president, in a momentary slip of his unprecedented refusal to concede his election defeat and help Biden prepare to take power.

Trump broke his silence after a week without on-camera comments, speaking at a Rose Garden event to herald the imminent authorization of a coronavirus vaccine.

During a short speech about the vaccine work, Trump insisted that he would never again call for a lockdown to curb the virus's spread. Then he added, "Whatever happens in the future, who knows which administration it will be, I guess time will tell."

The hint of doubt came despite him continuing to claim that mass fraud -- for which no evidence has been produced -- robbed him of victory in the November 3 election.

Despite his own intelligence officials' declaration Thursday that the election was "the most secure in American history," Trump and his right-wing media allies show no sign of giving up their quest to get the results overturned.

"President Trump believes he will be President Trump, have a second term," spokeswoman Kayleigh McEnany said on Fox News.

Biden is steadily preparing for power, with many world leaders congratulating him on his victory. China was the latest nation on board, with a foreign ministry spokesman saying, "We express our congratulations."