WILMINGTON, Del. — Vice President Kamala Harris won the backing of more than half the Democratic delegates she needs to become her party’s nominee and set a new fundraising record Monday in her first 24 hours as a presidential candidate, as top Democrats rallied to her in their bid to defeat Republican Donald Trump.

Democrat Leaders Line Up Behind Harris

Aiming to put weeks of intraparty drama over President Joe Biden’s prospects behind them, prominent Democratic elected officials, party leaders and political organizations quickly lined up behind Harris. Worries over Biden’s fitness for office were replaced by fresh signs of unity after a seismic shift to the presidential contest that upended both major political parties’ carefully honed plans for the 2024 race.

Speaking to campaign staff in Wilmington, Delaware, Harris acknowledged the “rollercoaster” of the last several weeks, but expressed confidence in her new campaign team.

“It is my intention to go out and earn this nomination and to win,” she said. She promised to “unite our Democratic party, to unite our nation, and to win this election.”

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Harris spoke at length in praise of Biden, who called into the meeting from his home in Rehoboth Beach, Delaware, where he is recovering from COVID-19.

“The name has changed at the top of the ticket, but the mission hasn’t changed at all,” Biden said in his first public remarks since announcing his decision to step aside, promising he was “not going anywhere” and plans to campaign on Harris’ behalf.

He said of his decision to step aside, “It was the right thing to do.”

Biden Freed His Delegates By Withdrawing

Biden’s departure freed his delegates to vote for whomever they choose at next month’s convention. And Harris, whom Biden backed after ending his candidacy, was working to quickly secure support from a majority.

Big-name Harris endorsements Monday, including from Govs. Wes Moore of Maryland, Gretchen Whitmer of Michigan, J.B. Pritzker of Illinois and Andy Beshear of Kentucky, left a vanishing list of potential rivals.

House Speaker Emerita Nancy Pelosi, who had been one of the notable holdouts, initially encouraging a primary to strengthen the eventual nominee, said she was lending her “enthusiastic support” to Harris’ effort to lead the party.

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More than 1,200 pledged delegates have told The Associated Press or announced that they plan to support Harris at the convention — more than half the 1,976 benchmark set by Democratic National Committee rules.

Winning the nomination is only the first item on a staggering 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. She must also pick a running mate and pivot a massive political operation to boost her candidacy instead of Biden’s 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 1,000 staffers and a war chest that stood at nearly $96 million at the end of June. She added $81 million to that total in the first 24 hours after Biden’s endorsement, her campaign said — a presidential fundraising record — with contributions from more than 888,000 donors.

Surge of Interest After Harris Took Over

The campaign also saw a surge of interest after Harris took over, with more than 28,000 new volunteers registered since the announcement — a rate more than 100 times an average day from the previous Biden reelection campaign, underscoring the enthusiasm behind Harris.

Harris has been spending much of her time making more than 100 calls to Democratic officials to line up their support for her candidacy, according to a person familiar with the matter who spoke on the condition of anonymity to discuss the effort. She’s trying to move her party past the painful, public wrangling that had defined the weeks since Biden’s disastrous June 27 debate with Trump.

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 person said.

In a sign that the Democratic Party was moving to coalesce behind her, Harris quickly won endorsements from the leadership of several influential caucuses and political organizations, 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 chairs of the Congressional Progressive Caucus and 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.

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Notably, a handful of men who had already been discussed as potential running mates for Harris — Pennsylvania Gov. Josh Shapiro, North Carolina Gov. Roy Cooper and Arizona Sen. Mark Kelly — also swiftly issued statements endorsing her. Aides to Shapiro and Cooper confirmed that Harris spoke with them Sunday afternoon. In her brief call with Cooper, the North Carolina governor told Harris he was backing her to be the Democratic nominee, according to Cooper spokeswoman Sadie Weiner.

But former President Barack Obama 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.

Sen. Joe Manchin Will Not Run

West Virginia Sen. Joe Manchin, who left the party earlier this year but considered re-registering as a Democrat to vie for the nomination against the vice president, told CBS News on Monday that he would not be a candidate.

In an indication of how she will have to balance her day job and her new role as candidate, Harris made her first public appearance Monday morning at the White House, where she opened her address to National Collegiate Athletic Association championship teams by praising Biden’s “unmatched” legacy, saying she was “deeply grateful for his service to our nation.”

Harris was filling in at the event for Biden, who was recovering at his home in Rehoboth Beach, Delaware after contracting COVID-19 last week.

Biden planned to discuss his decision to step aside later this week in an address to the nation.

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The Democratic National Convention is scheduled to be held Aug. 19-22 in Chicago, but the party had announced it would hold a virtual roll call to formally nominate Biden before in-person proceedings begin. The convention’s rules committee is scheduled to meet this week to finalize its nomination process and it is unclear how it will be adjusted to reflect Biden’s exit.

Congressional Hispanic Caucus chairwoman Nanette Barragan, who emphasized that she was “all in” behind the vice president, said she spoke Sunday with Harris, who communicated that she preferred to forgo a virtual roll call for the nomination process and instead hold a process that adheres to regular order.

The Democratic National Committee’s chair, Jaime Harrison, said in a statement that the party would “undertake a transparent and orderly process” to select “a candidate who can defeat Donald Trump in November.”