He also addressed the millions of Americans who remain out of work and are struggling to pay rent or buy food.

He spoke about Trump's election rigging claims and attempts to stop the vote-counting.

"Your vote will be counted. I don't care how hard people try to stop it. I will not let it happen. People will be heard," he said.

"Our journey is towards a more perfect union and it keeps moving on. In America, we hold strong views, we have strong disagreements and that is OK.

"Strong disagreements are inevitable in a democracy. Strong disagreements are healthy. They are a sign of a vigorous debate of deeply held views but we have to remember, the purpose of our politics isn't total unrelenting on warfare.

"No, the purpose of our politics, the work of the nation isn't to fan the flames of conflict but to solve problems.

"To guarantee justice, to give everybody a fair shot and improve the lives of our people. We may be opponents but we are not enemies, we are Americans."

Biden said he's going to be the first Democrat to win Arizona in 24 years and the first in Georgia for 28.

He also called for patience as the votes aren't counted.

"We have rebuilt the blue wall in the middle of the country that crumbled just years ago. Pennsylvania, Michigan, Wisconsin, the heartland of this nation," he said.

"I know watching these vote tallies on TV moves very slow and is as low as it goes, it can be numbing.

"But never forget, the tallies are not just numbers, they represent votes and voters.

"Men and women who exercise their fundamental rights to have their voice heard. And what is becoming clear each hour is that record numbers of Americans of all races, faiths, religions, chose change over more of the same."

Biden had leads in Pennsylvania, Nevada and Georgia, putting him in a stronger position to capture the 270 Electoral College votes needed to take the White House. The winner will lead a country facing a historic set of challenges, including the surging pandemic and deep political polarisation.

The focus is on Pennsylvania, where Biden leads Trump by more than 16,000 votes, and Nevada, where he leads by about 22,000. Americans spent a third full day after the election without knowing who will lead them for the next four years. The prolonged process added to the anxiety of a nation whose racial and cultural divides were inflamed during the heated campaign.

Trump's campaign remains quiet — a dramatic difference from yesterday, when it held a morning conference call projecting confidence and held a flurry of hastily arranged press conferences announcing litigation in key states.

A handful of states remain: Georgia, North Carolina, Pennsylvania and Nevada are all too early to call. In all four states the margins between Trump and Biden are too narrow and the number of ballots left to be counted too great to declare a victor.

In Pennsylvania, officials were not allowed to begin processing mail-in ballots until election day under state law. In Nevada, there were a number of provisional ballots cast by voters who registered on election day, and officials had to verify their eligibility. And recounts could be triggered in both Pennsylvania and Georgia.

With his pathway to reelection quickly narrowing, Trump tested how far he could go in using the trappings of presidential power to undermine confidence in the vote.

On Thursday (US time), he advanced unsupported accusations of voter fraud to falsely argue that his rival was trying to seize power. It was an extraordinary effort by a sitting American president to sow doubt about the democratic process.

"This is a case when they are trying to steal an election, they are trying to rig an election," Trump said from the podium of the White House briefing room.

He took to Twitter late Friday to pledge further legal action, tweeting "Joe Biden should not wrongfully claim the office of the President. I could make that claim also. Legal proceedings are just now beginning!"

Trump did indeed claim that he won, late on election night. He also tweeted that he had "such a big lead in all of these states late into election night, only to see the leads miraculously disappear as the days went by," although it was well known that votes cast before election day were still being legally counted.

Biden spent Thursday trying to ease tensions and project a more traditional image of presidential leadership. After participating in a coronavirus briefing, he declared that "each ballot must be counted".

"I ask everyone to stay calm. The process is working," Biden said. "It is the will of the voters. No one, not anyone else who chooses the President of the United States of America."

Trump's erroneous claims about the integrity of the election challenged Republicans now faced with the choice of whether to break with a president who, though his grip on his office grew tenuous, commanded sky-high approval ratings from rank-and-file members of the GOP. That was especially true for those who are eyeing presidential runs of their own in 2024.

Maryland GOP Governor Larry Hogan, a potential presidential hopeful who has often criticised Trump, said unequivocally: "There is no defence for the President's comments tonight undermining our Democratic process. America is counting the votes, and we must respect the results as we always have before."

But others were more confrontational on behalf of the President. House Minority Leader Kevin McCarthy, in an interview with Fox News, falsely insisted that Trump "won" the election and claimed that illegal votes were being counted.

"Everyone who's listening, do not be quiet, do not be silent about this. We cannot allow this to happen before our very eyes," he said. "Join together and let's stop this."

Senator Josh Hawley also supported Trump's claims, tweeting "If last 24 hours have made anything clear, it's that we need new election integrity laws NOW."

Trump's campaign engaged in a flurry of legal activity, saying it would seek a recount in Wisconsin and had filed lawsuits in Pennsylvania, Michigan and Georgia.

But judges in the three states quickly swatted down legal action. A federal judge who was asked to stop vote counts in Philadelphia instead forced the two sides to reach an agreement without an order over the number of observers allowed.

"Really, can't we be responsible adults here and reach an agreement?" an exasperated US District Judge Paul Diamond said during an emergency hearing on Thursday evening. "The whole thing could [soon] be moot."

The Trump campaign said it was confident the President would ultimately pull out a victory in Arizona, where votes were also still being counted, including in Maricopa County, the state's most populous area. The AP has declared Biden the winner in Arizona.

An official winner is yet to be declared.