Joe Biden has all but claimed the presidency of the United Sates, telling the nation that the numbers are clear that he will win the race against Donald Trump.

Appearing on stage at Wilmington with his running mate Kamala Harris,  Mr Biden talked up what he expects to be Democrats gains in traditional Republican strongholds of Georgia and Arizona.

Mr Biden said he would not be waiting for Mr Trump to concede before getting to work on tackling the big issues facing the USA, with coronavirus response at the top of the list.

“I know watching these vote tallies on TV moves very slow and is as low as it goes, it can be numbing,” Mr Biden said. “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.

They have given us a mandate for action on COVID, the economy, climate change, systemic racism. They have made it clear that they want the country to come together, not continue to pull apart.

“I want everyone, everyone to know on day one, we are going to put our plan to control this virus into action. We can’t save any of the
lives lost, any that have been lost, but we can save a lot of lives in the months ahead.”

Biden’s speech came as CNN reported that Mr Trump’s chief of staff Mark Meadows had in the pst few days tested positive for coronavirus, on the third consecutive day of US infections above 100,000.

Earlier on Saturday (AEST) Mr Biden took the lead in Pennsylvania, with its 20 electoral votes being all he needed to claim the presidency.

Biden is within striking distance of claiming the United States presidency after stretching his lead in Pennsylvania throughout Saturday (AEST).

The Democrat has also taken the lead in three other key states – Georgia, Nevada and Arizona – with a win in two out of three of them also able to place Mr Biden in the top job.

President Donald Trump has vowed to continue a series of legal challenges that experts described as unlikely to succeed in altering the election outcome.

Mr Biden had scheduled an address the nation during prime time television, but it has been delayed with no result declared.

That prompted yet another controversial tweet from Mr Trump, who claimed Mr Biden should not “wrongfully claim” the presidency.

Tweet from @realDonaldTrump

Mr Biden would have none of that, saying in his speech that he was on track to have”over 300 electoral college votes”.

“Look at the national numbers. We’re going to win this race a clear majority with the nation behind us,” he said.

“We have gotten over 74 million votes. I’m going to repeat that, 74 million votes. That is more than any presidential ticket has ever gotten in the history of the United States of America. And the vote total is still growing.

“We are beating Donald Trump by over four million votes. That is a margin that is still growing as well.

“We are proving again what we have for 244 years, proving that democracy works. 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. Our journey is towards a more perfect union and it keeps moving on.

Pennsylvania is a crucial state that both sides need to win in order to secure the 270 Electoral College Votes needed to become president.

Mr Biden is now leading by 28,833 votes in Pennsylvania, with mail ballots continuing to favour the challenger. Mr Trump won the state in 2016 by some 45,000 votes.

With Mr Biden currently on 253 Electoral College votes, winning Pennsylvania’s 20 electoral votes would give the former vice president more than 270.

Mr Biden has also overtaken Mr Trump in Georgia where he now holds a narrow lead of around 4400 votes, with Georgia’s secretary of state declaring a recount would occur because the numbers were “too close to call”.

As counting continues, Mr Biden is now pulling ahead in Nevada by 22,657 votes, although his lead is shrinking in Arizona, where he leads by almost 30,000.

• Related: The 46th president? Joe Biden’s road from Scranton to the White House

Anti-Trump protesters gather outside the Philadelphia Convention Center. Photo: Getty

Three days after polls closed in the election, Mr Biden has a lead of 253 to 214 in the state-by-state Electoral College vote, according to a BBC tally.

In both Pennsylvania and Georgia, Mr Biden overtook Mr Trump on the strength of mail-in ballots that have been favouring the Democrat during the final stages of the count.

The counting in Pennsylvania, Arizona and Nevada is still expected to take days to complete.

Meanwhile the White House issued a statement from Mr Trump stating: “We will pursue this process through every aspect of the law to guarantee that the American people have confidence in our government.

“I will never give up fighting for you and our nation.

“This is no longer about any single election. This is about the integrity of our entire election process.”

Mr Trump’s general counsel, Matt Morgan, has claimed the elections in Georgia, Nevada and Pennsylvania all suffered from improprieties and that Mr Trump would eventually prevail in Arizona.

“This election is not over,” he said.

“Biden is relying on these states for his phoney claim on the White House, but once the election is final, President Trump will be re-elected.”

A poll watcher monitors the counting of ballots at the Allegheny County elections warehouse in Pittsburgh, Pennsylvania. Photo: Getty

Election officials in those states have said they are unaware of any irregularities.

Republicans cautious in supporting ‘fraud’ claims

Some of Mr Trump’s fellow Republicans in Congress have hinted that he ought to tone down his rhetoric.

Amid Trump’s repeated and unfounded allegations of election fraud, Senator Roy Blunt, a member of the Republican leadership, told reporters that “at some point” the White House will have to be able to take such allegations to court and lay out the evidence.

“I also don’t think it’s unreasonable for Biden to accept the unofficial result and do whatever he thinks he should do,” Blunt said.

Some senior Republicans voiced support for the president’s claims. House of Representatives Minority Leader Kevin McCarthy said on Fox News: “President Trump won this election. So everyone who’s listening, do not be quiet.”

Senate Judiciary Committee Chairman Lindsey Graham, an avid Trump supporter, told Fox News that he was prepared to donate $A687,966 to Trump’s legal efforts in multiple states.

The Republican National Committee is aiming to raise at least $A83 million to help finance Trump’s legal battles, sources told Reuters.

But other Republicans in Congress were not as excited about a drawn-out battle and its toll on America if it becomes clear that Biden won the election fair and square.

Senator Rob Portman of Ohio, which Trump won handily on Tuesday, echoed Senate Majority Leader Mitch McConnell in urging that ballots be counted in accordance with each state’s laws.

“I hope we can reach a final resolution as quickly as possible,” he said in a statement.

Senator Mitt Romney, the 2012 Republican presidential candidate, knows the agony that can come with defeat. But he castigated Trump for claiming the election was being stolen.

“Doing so damages the cause of freedom here and around the world… and recklessly inflames destructive and dangerous passions,” Romney said on Twitter.

Some 30 per cent of American Republicans accept Trump’s claim that he won the election, though a bipartisan majority of Americans do not, according to a Reuters/Ipsos poll published on Thursday.

Tweet from @MittRomney

House speaker Nancy Pelosi said Mr Biden had a “tremendous mandate” after a historic voter turnout helped propel him to within the presidency.

“It’s a happy day for our country because Joe Biden is a unifier, he is determined to bring people together,” she said.

Georgia recount

Georgia will undertake a recount as Joe Biden took the lead with the narrowest of margins and Mr Trump made claims on Twitter about “missing ballots”.

Georgia’s secretary of state Brad Raffensperger said he expected ballots to be counted again due to the small margin.

“With a margin that small, there will be a recount,” Brad Raffensperger, said.

-with AAP