US President-elect Joe Biden speaks during a cabinet announcement event in Wilmington, Delaware on Tuesday. Biden introduced a seasoned national security team he said was prepared to resume US leadership in the world after the departure of President Donald Trump. Photo: AFP

US President-elect Joe Biden said Wednesday that Americans "won't stand" for attempts to derail the US election outcome, as President Donald Trump called for the results to be overturned.

In a speech on the eve of the Thanksgiving holiday, Biden said in his hometown of Wilmington, Delaware that Americans "have full and fair and free elections, and then we honor the results."

"The people of this nation and the laws of the land won't stand for anything else," he said.

Biden's statement signaled a hardening line against Trump who for more than three weeks has been touting conspiracy theories, with no meaningful evidence, that Biden stole victory on November 3.

Trump, who also issued a full pardon for former security aide Michael Flynn, convicted of lying to the FBI over Russia contacts, dug his heels in.

"We have to turn the election over," he told Republican supporters in Pennsylvania.

"This election was rigged," Trump said via telephone, repeating several claims of vote tampering that have been shot down in courtrooms across the country. 

Trump had been due earlier to appear in person at the Republican meeting, which took place near the Civil War battlefield site of Gettysburg. He canceled at the last minute.

The gathering, which also featured Trump's controversial personal lawyer Rudy Giuliani, was falsely portrayed by the president on Twitter as a "very important Pennsylvania State Senate hearing."

It was in fact held in a hotel in the small town and, rather than an official hearing, was merely a forum for Trump's ardent supporters to push his evidence-free claims.

Biden won Pennsylvania by a margin of 80,000 votes on November 3, helping him assemble a convincing nationwide victory and making Trump a one-term president.

Trump, who tore up countless norms during his four years in power, is carving out new territory with his refusal to concede to Biden.

Supporters suggest he is already eying an announcement of running for president again in 2024.

Building his brand ahead of a new campaign might be one explanation for the real estate tycoon's dogged pursuit of such a lost cause.

AFP