Biden, who has pledged to act quickly to provide more resources to fight the health crisis after he is inaugurated on January 20, told a group of workers and business owners that any emergency aid approved by Congress before he takes office would be only a "down payment."
Republicans and Democrats are trying to resolve a months-long standoff in Congress over a stimulus package for businesses affected by coronavirus shutdowns as well as the millions who have lost jobs.
"My transition team is already working on what I will put forward to the next Congress to address the multiple crises we’re facing, especially the economic crisis and Covid," Biden told the workers at a roundtable in his home state of Delaware.
More than 270,000 people in the United States have died of Covid-19, which is resurgent across the country. The United States leads the world in the number of infections as well as the number of deaths reported every day.
"I don't want you to give up hope," Biden told the workers. "Hang on, we'll get through this."
Trump has refused to concede the November 3 election and his lawyers continue to file legal challenges to the outcome, alleging electoral fraud without providing evidence. State and federal election officials have repeatedly said there is no such evidence. Most of the lawsuits have been rejected by judges.
At a White House holiday reception on Tuesday night, Trump appeared to acknowledge that those efforts could fail and in that case he would run again.
"We are trying to do another four years," he told the assembled group, according to a Republican source who was at the event. "Otherwise, I’ll see you in four years.”
A source familiar with the internal debate says Trump has been discussing with advisers not attending the inauguration ceremony on January 20 but instead announcing his 2024 bid that day. The source said there had been no decision. Only a handful of outgoing US presidents have chosen to miss the swearing-in of their successors.
Trump tweeted a video on Wednesday in which he repeated unfounded accusations about the election being rigged and said he would keep up the fight against the outcome. Trump, who spoke from behind a lectern with the presidential seal, posted a two-minute version of the message on Twitter with a link to a 46-minute version on Facebook.
A day earlier, Attorney General William Barr, who has long been seen as a Trump ally, said the Justice Department has found no evidence of widespread fraud.
Trump's claims have gained traction among his followers, however, helping to raise as much as $US170 million ($NZ240 million) for an "Election Defense Fund" that can be used for a wide variety of future political activities, including another run for the presidency, according to media reports.
'VIOLENT RHETORIC'
On Wednesday, Georgia Secretary of State Brad Raffensperger said Biden was headed for victory after the state's second recount and criticised Trump for fomenting false claims.
"Even after this office request that President Trump try and quell the violent rhetoric being born out of his continuing claims of winning the states where he obviously lost, he tweeted out 'expose the massive voter fraud in Georgia,'" said Raffensperger, a Republican.
"This is exactly the kind of language that is at the base of a growing threat environment for election workers who are simply doing their jobs."
Biden has already selected many of his top national security and economic advisers, although it is unclear how many will win confirmation in a closely divided Senate, control of which will be determined by a pair of January runoff elections in Georgia.
Biden told the New York Times in an interview on Tuesday evening that he would try to help resolve the standoff in Congress over the coronavirus aid.
"You have over 10 million people out there who are worried (how) they can pay their next mortgage payment,” Biden said in the interview, and “you have a significantly higher number of people who have no ability to pay their rent.”
Failure on the issue could have political consequences for Republicans, Biden told the newspaper.
“When you have cops and firefighters and first responders across the board being laid off, when you’re not getting the kind of distribution of vaccines out to rural America, it has to have some consequences,” he was quoted as saying.
Republican Senate Majority Leader Mitch McConnell has begun circulating new draft legislation after a bipartisan group of lawmakers unveiled a $US908 billion (NZ$1.28 trillion) package.
Britain approved Pfizer Inc 's Covid-19 vaccine on Wednesday, the first country to do so. Once similar approval is granted by US regulators, health officials plan to begin vaccinating Americans as soon as mid-December.
