KAMALA Harris has moved swiftly to attract Democratic delegates to her campaign for the White House after Joe Biden stepped aside amid concerns he would be unable to defeat Donald Trump.

Biden’s exit on Sunday, prompted by concerns over his fitness for office, was a seismic shift to the presidential contest that upended both parties’ plans for the race.

Aiming to put weeks of drama over Biden’s candidacy behind them, prominent Democratic elected officials, party leaders and political organisations quickly lined up behind Harris in the hours after the president announced he was dropping out of the race.

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A number of celebrities, including Star Trek actor George Takei and Oscar-winning actress Jamie Lee Curtis, have also urged people to support Harris.

Harris, who Biden backed after ending his candidacy, is the only declared candidate so far and was working to quickly secure endorsements from a majority of delegates.

(Image: Twitter/X)

It is the first item on a big political to-do list for her after Biden’s decision to exit the race, which she learned about on a Sunday morning call with the president.

If she wins the nomination, she must also pick a running mate and shift a massive political operation to boost her candidacy with just over 100 days until election day.

On Sunday afternoon, Biden’s campaign formally changed its name to “Harris for President”, reflecting that she is inheriting his political operation of more than 1000 staff and a war chest that stood at nearly 96 million dollars (£74 million) at the end of June.

Harris spent much of Sunday surrounded by family and staff, making more than 100 calls to Democratic officials to line up their support for her candidacy, according to a source.

It comes as she tries to move her party past the painful public wrangling that had defined the weeks since Biden’s disastrous June 27 debate with Trump (below).

Speaking to party leaders, Harris expressed gratitude for Biden’s endorsement, but insisted she was looking to earn the nomination in her own right, the source said.

She quickly won endorsements from the leadership of several influential caucuses and political organisations, including the AAPI Victory Fund, which focuses on Asian American and Pacific Islander voters, the Collective PAC, focused on building black political power, and the Latino Victory Fund, as well as the heads of the Congressional Progressive Caucus, the Congressional Hispanic Caucus and the entire Congressional Black Caucus.

Harris, if elected, would be the first woman and first person of south Asian descent to be president.

A handful of men who had already been discussed as potential running mates for Harris — Pennsylvania governor Josh Shapiro, North Carolina governor Roy Cooper and Arizona senator Mark Kelly — swiftly issued statements endorsing her.

Former president Barack Obama (below) held off on an immediate endorsement, as some in the party have expressed worry that the quick shift to Harris would appear to be a coronation, instead pledging his support behind the eventual party nominee.

West Virginia senator Joe Manchin, who left the party earlier this year to become an independent, is considering re-registering as a Democrat to compete for the nomination against the vice president, according to Jonathan Kott, a longtime adviser to Manchin.

Harris is to make a public appearance on Monday morning at the White House, where she is scheduled to speak at an event honouring National Collegiate Athletic Association championship teams. She is filling in for Biden, who is recovering after contracting Covid-19 last week.

Harris, in a statement, praised the president’s “selfless and patriotic act” in deciding to leave the race and said she intends to “earn and win” her party’s nomination.

“I will do everything in my power to unite the Democratic Party — and unite our nation — to defeat Donald Trump and his extreme Project 2025 agenda,” she said.

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Biden plans to discuss his decision to step aside later this week in an address to the nation. He wrote in a letter posted on Sunday: “I believe it is in the best interest of my party and the country for me to stand down and to focus solely on fulfilling my duties as President for the remainder of my term.”

Nearly 30 minutes after he delivered the news that he was ending his campaign, he threw his support behind Harris.

“Today I want to offer my full support and endorsement for Kamala to be the nominee of our party this year,” he said in another post. “Democrats — it’s time to come together and beat Trump.”