US President-elect Joe Biden has said it is "embarrassing" for Donald Trump not to concede defeat in the presidential election.

Joe Biden, who has won the expected election results and is in the process of liaising with world leaders, has stressed that no one can stop the leadership from shifting.

The debate erupted when President Trump made an unconfirmed claim on Twitter that he would win in the end, despite the fact that most major media outlets have confirmed his defeat in the election.

State results have not been officially confirmed and votes are being counted in some places. The final election results will be announced on December 14 at a meeting of the American Electoral College.

What did Joe Biden say?

Democrat Biden was asked by a Delaware reporter on Tuesday what he thought of Trump's failure to concede defeat, to which he replied, "I think it's a shame."

"One thing I can say is that it will not benefit the president's legacy ... At the end of the day, you should know that everything will be clear on January 20. Here he was referring to the handover ceremony.

While Biden is preparing to take over the presidency, he has also established contacts with world leaders.

British Prime Minister Boris Johnson, French President Emmanuel McKeown and German Chancellor Angela Merkel spoke to him on Tuesday.

"I've told them I'm back in the United States," Biden said. We are returning to the game.

While he and newly elected Vice President Kamala Harris are working on future plans, Trump-appointed officials are helping to delay the transition to the US presidency.

The US General Services Administration provides information on the funding of various agencies and the new administration after the election. The agency has not yet recognized Biden as president-elect.

"I don't think anything can slow us down," Biden said.

What are Trump and his allies saying?

On Tuesday, President Trump wrote on Twitter that "there has been a lot of corruption in the counting of votes ... We will win.

But Twitter has called his tweets controversial.

The president says Biden won the election only because of corruption in the presidential election. So far, however, no evidence has been provided by President Trump to substantiate the allegations.

US Secretary of State Mike Pompeo, who is considered a staunch supporter of Trump, said on Tuesday that once all legitimate votes were counted, it would prove that the second term of the Trump administration has begun.

Meanwhile, some senior Republican leaders did not acknowledge Biden's expected victory. When asked about this, Senator Ron Johnson replied, "There is no justification for congratulating (Biden)."

Senator Roy Blunt says Trump may never have lost.

Senate Republican leader Mitch McConnell says Trump has the right to sue in a highly competitive state like Pennsylvania.

What progress has been made in allegations of election fraud?

A postal worker in Pennsylvania has claimed that authorities rigged postal ballots. He claimed that a postmaster in Pennsylvania had asked employees to record votes in the past so that they could be counted.

He took the oath and legally filed the claim in a committee of the House of Representatives. But the committee says he withdrew his allegations when questioned by the US Postal Service's inspector general.

The statement said that in a video posted on YouTube, the man said, "I did not record this statement. It didn't happen and you will know about it by tomorrow. "

Trump retweeted the video and praised the man.

Trump supporters have called for legal action based on the man's statement.