US president-elect Donald Trump and President Joe Biden have met for the first time since Trump won back the White House last week, with both men promising a smooth transfer of power in January.

The two leaders sat side by side before a roaring fire in the Oval Office, a peaceful scene that belied tensions between them.

Biden defeated Trump in the 2020 election but dropped out of the 2024 race in July after a disastrous debate with the Republican Trump.

He handed his candidacy to Vice President Kamala Harris, who lost.

“We’re looking forward to having, like we said, a smooth transition, do everything we can to make sure you’re accommodated, what you need,” Biden said.

“Welcome, welcome back.”

“Politics is tough, and it’s many cases not a very nice world, but it is a nice world today and I appreciate very much a transition that’s so smooth it’ll be as smooth as it can get and I very much appreciate that, Joe,” said Trump, who takes over on January 20.

Reporters shouted questions but were quickly ushered out.

Sharp contrast

The two men have hurled criticism at each other for years, and their respective teams hold vastly different positions on policies from climate change to Russia to trade.

Biden, 81, has portrayed Trump as a threat to democracy while Trump, 78, has portrayed Biden as incompetent.

Trump made claims of widespread fraud in the 2020 election even though his own attorney general, recounts and investigations found no evidence of that.

Trump’s motorcade rolled through the heavily guarded White House gate and the former and future Republican president was greeted in the Oval Office by Biden, a Democrat who defeated him in the 2020 election.

Outside on the White House driveway, a massive crowd of journalists gathered in anticipation of the big event.

Trump celebrated his victory earlier in the day with Republicans in the House of Representatives. They are projected to have won the majority of seats in the House.

“Isn’t it nice to win? It’s nice to win. It’s always nice to win,” Trump said.

“The House did very well.”

Path to inauguration

Outside the White House gates, signs of the impending power transfer were evident with construction already under way for stands for VIP guests to sit during the parade that happen after Trump is inaugurated.

Although Biden intended to use the meeting to show continuity, the transition itself is partially stalled.

Trump’s team, which has already announced some members of the incoming president’s cabinet, has yet to sign agreements that would lead to office space and government equipment as well as access to government officials, facilities and information, according to the White House.

“The Trump-Vance transition lawyers continue to constructively engage with the Biden-Harris Administration lawyers regarding all agreements contemplated by the Presidential Transition Act,” said Brian Vance, a spokesman for the Trump transition, referring to the law that governs the transfer of power.

Valerie Smith Boyd, director of the Partnership for Public Service’s Center for Presidential Transition, a non-profit that advises incoming administrations, said the agreement underscored that the US had only one president at a time and included pledges to sign pacts not to profit off information provided in the transition.

“That needs to be signed for interaction to begin with federal agencies,” she said.

“Everything is hinging on that.”

Meanwhile, Trump has nominated named firebrand Republican Matt Gaetz as his nominee for attorney-general, Republican Senator Marco Rubio as secretary of state, and former Democratic representative Tulsi Garbbard as director of national intelligence.

-AAP