Joe Biden is set to nominate a former ambassador to France as his representative to the UK.
The US president plans to select Jane Hartley, who was Barack Obama’s ambassador in Paris, for the role in London.
Ms Hartley has been a prolific Democrat fundraiser, raising more than $500,000 for Mr Obama’s re-election campaign in 2012.
Those under consideration as Mr Biden’s ambassador to the Court of St James’s have, at various times, reportedly included Michael Bloomberg, the billionaire former mayor of New York, and Colin Powell, the former secretary of state.
Others in the frame have included James Costos, an entertainment executive who was Mr Obama’s ambassador to Spain, and Ted Kaufman, a friend of Mr Biden’s who was once his chief of staff.
Bob Iger, the former chief executive of Disney, and a major donor to Mr Biden, was also said to have been under consideration.
The White House also discussed choosing a black nominee because there had never been a black US ambassador to the UK, The Washington Post reported.
Bob Iger, the former Disney boss, was said to have been considered
Ms Hartley would be a surprise choice as other people raised more money for Mr Biden in the 2020 campaign.
But she was a significant fundraiser and supportive of him when he was struggling in polls early on.
The White House declined to comment after her selection was reported by The Washington Post.
It followed a long search to settle on a nominee, which has perplexed some US and British officials considering the high profile of the role.
The job usually goes to a friend or donor of the incoming president. Donald Trump nominated Woody Johnson, the owner of the New York Jets football team.
Ms Hartley was a Democrat official in Jimmy Carter’s administration in the late 1970s. She has since worked in marketing and communications, and as a political consultant.
The confirmation process, which is being stalled by Republicans in the Senate, could take months.
The US state department is sending Phil Reeker, a seasoned diplomat, to London as a stopgap to take charge of the US Embassy as Chargé d’Affaires in the interim.