Washington DC - President Joe Biden urged Americans Thursday to lower the political temperature after Donald Trump's crushing election win over Kamala Harris, saying in a conciliatory address to the nation that he would ensure a peaceful transition of power.

In a solemn speech from the White House, Biden also said the result should "lay to rest" doubts about the integrity of the US election system fueled by Trump's refusal to acknowledge his own 2020 defeat by the Democrat.

"Something I hope we can do, no matter who you voted for, is see each other not as adversaries but as fellow Americans. Bring down the temperature," Biden said.

Staff rose to their feet, cheered, and clapped as Biden arrived in the famed Rose Garden. The 81-year-old dropped out of the race against Trump in July and handed the Democratic nomination to Harris, his vice president.

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Biden said he had called Republican Trump to congratulate the twice-impeached former president and assure him there would be a "peaceful and orderly" transition.

"On January 20, we'll have a peaceful transfer of power here in America," said Biden, whose inauguration Trump had refused to attend.

The outgoing president also urged supporters not to lose hope after the re-election of Trump, who is likely to dismantle many of Biden's policies as soon as he returns to the White House.

"Remember, a defeat does not mean we are defeated," he said.

Biden's comments were in stark contrast to billionaire Trump, whose election defeat denial four years ago culminated in the violent January 6, 2021 assault by Trump's supporters on the Capitol.

Biden has invited Trump to meet at the White House, for what would be their first encounter since Biden's disastrous debate performance against Trump in June that forced him out of the race.