Joe Biden promised a black woman on the Supreme Court 'in exchange' for crucial endorsement in 2020 election

President Joe Biden was reportedly forced into promising to nominate the first black woman to sit on the Supreme Court in exchange for a key senator's support that helped turn his 2020 election campaign around.

A number of judges are being considered by Mr Biden for an upcoming vacancy on the US’s highest court after it emerged on Wednesday that one of its three liberal judges was planning to step down.

All are black women, suggesting Mr Biden intends to honour a campaign pledge made in February 2020 at a debate ahead of the crucial South Carolina primary.

"Everyone should be represented," he said at the time. "The fact is, what we should be doing — we talked about the Supreme Court. I’m looking forward to making sure there’s a black woman on the Supreme Court to make sure we in fact get every representation. Not a joke."

“It’s required that they have representation now. It’s long overdue,” he said.

But according to the authors of a book called ‘Lucky: How Joe Biden Barely Won the Presidency’, he was strong-armed into making that promise in return for the much-needed endorsement of Jim Clyburn, House majority whip and one of the highest ranking African-American members of Congress.

When Mr Biden still hadn’t made the pledge by halfway through the South Caroline primary debate, Mr Clyburn took the presidential hopeful aside and chided him, according to Jonathan Allen, an adjunct professor at Northwestern University, and Amie Parnes, senior political correspondent at The Hill.

"You've had a couple of opportunities to mention naming a black woman to the Supreme Court," Mr Clyburn reportedly told Mr Biden, according to NBC.

"I'm telling you, don't you leave the stage tonight without making it known that you will do that."

By the end of the event, Mr Biden made the pledge and the next day, Mr Clyburn endorsed him.

His support came at a crucial time when Mr Biden's campaign had failed to win any of his three campaigns for the White House, losing caucuses in Iowa and Nevada and a primary in New Hampshire.

Mr Biden went on to easily win South Carolina’s primary, bringing his presidential bid back from the brink and giving him new momentum.

Polls at the time suggested that his victory there was in large part due to African-American support, with Mr Clyburn’s endorsement a significant factor for those voters.

Mr Biden is expected to hold an event at the White House on Thursday to formally announce Justice Stephen Breyer’s retirement, according to a person briefed on the planning who was not authorized to publicly discuss it in advance.

The frontrunners to replace him are US Circuit Judge Ketanji Brown Jackson, US District Judge J. Michelle Childs and California Supreme Court Justice Leondra Kruger, according to aides and allies.