US President Donald Trump has said he will leave the White House if the Electoral College votes for President-elect Joe Biden, the closest he has come to conceding the 3 November election, even as he reiterated his unfounded claims of massive voter fraud.

Speaking to reporters on the Thanksgiving holiday, Mr Trump said if Mr Biden - who is due to be sworn in on 20 January - is certified the election winner by the Electoral College, he will depart the White House.

But Mr Trump said it would be hard for him to concede under the current circumstances and declined to say whether he would attend Mr Biden's inauguration.

The electors are scheduled to meet on 14 December.

"This election was a fraud," he insisted, while offering no concrete evidence of such voting irregularities.

Mr Biden won the 3 November presidential election with 306 Electoral College votes - many more than the 270 required - to Mr Trump's 232.

Mr Biden also leads Mr Trump by more than 6 million in the popular vote tally.

Mr Trump has so far refused to concede the election and continues to claim without evidence that the election was marred by widespread fraud, and that he and not Mr Biden won it.

Both Mr Biden and Mr Trump stayed close to home to celebrate Thanksgiving as the Covid-19 pandemic surged across the country.

Mr Biden spent the holiday in the small seaside town of Rehoboth, Delaware, where he and his wife Jill have a holiday home.

The former vice president, appearing with his wife in a video message posted to his Twitter account, said his family typically holds a large gathering on the island of Nantucket off Massachusetts, but would remain in Delaware this year "with just a small group around our dinner table" because of the pandemic.

In the presidential-style address to a nation that has lost more than 260,000 lives to the virus, Mr Biden said Americans were making a "shared sacrifice for the whole country" and a "statement of common purpose" by staying at home with their immediate families.

"I know this isn't the way many of us hoped we'd spend our holiday. We know that a small act of staying home is a gift to our fellow Americans," said Mr Biden. "I know better days are coming."

Mr Trump often likes to celebrate holidays at his Mar-a-Largo resort in Florida. But he remained in the Washington area, spending part of the morning at his Trump National Golf Club in Virginia where he played a round of golf.

It was a far cry from last year when he made a surprise visit to Afghanistan, where he served turkey to US troops before sitting down to eat Thanksgiving dinner with them.

This time, Mr Trump spoke by video link from the White House to members of the military.