In the national popular vote count - a metric to gauge popularity but with no legal meaning - Biden leads Trump, with about 80 million votes to some 73.9 for the incumbent.
Asked if he'll attend the inauguration, Trump said he knows the answer but doesn't want to say.
When pressed further if he would concede, Trump snapped at the reporter, calling him a "lightweight" and said, "Don't talk to me that way".
Mr Biden leads Mr Trump 306 votes to 232 under the electoral college system used to pick U.S. presidents. But undeterred, the Trump campaign is pushing forward with legal challenges in many states hoping to demonstrate that widespread election fraud took place.
In his Thanksgiving Day remarks, Trump, however, said it will be a mistake if the Electoral College were to elect Biden.
During his 25-minute back-and-forth with the media, the president continued to push unproven conspiracy theories about voting machines switching votes from him to Biden and alleged Biden only received a record 80 million votes through election fraud. The US Congress will gather on January 6, 2021 to formally certify the Electoral College results and declare the victor of the White House.
Interior Health monitoring community COVID-19 cluster in Revelstoke
Of the new cases confirmed on Friday, more than half involved residents in either Toronto (494 new cases) or Peel (517). According to the province's epidemiology report, 13 of the 20 deaths were people living in long-term care homes.
Earlier this week, Mr Biden urged Americans to hold smaller Thanksgiving celebrations, saying that "I know that we can and will beat this virus". Wisconsin and Arizona, two more states that flipped to Biden, are set to certify their results next week."Massive fraud has been found".
Several mainstream media outlets have called the race for Biden and officials in battleground states such as Pennsylvania, Michigan, and Georgia have taken steps toward certifying election results.
The normally routine process of transitioning from one president to another and confirming the result has been derailed by President Trump's refusal to concede.
Showing that he intends to stay in the political fray until the end of his term, Trump said on Thursday he would travel on December 5 to Georgia, a once solidly Republican state he lost narrowly to Biden, to campaign for two Republican U.S. Senate candidates. "Just so you understand, this election was a fraud". I think it's a possibility. He said: "People are very disappointed that we were robbed". "I hope the individuals that were involved in the attack on him, and conjuring evidence against him and all the things that happened are being investigated, and that will come to fruition here very soon".
"Time is not on our side", he said, in a rare admission of weakness. "And I would have won by a tremendous amount", Trump said, quickly correcting himself to say, "And I did win by a tremendous amount".
Supporters suggest he is already eyeing a run for president in 2024.