Kamala Harris pledged to unite the Democratic Party and win the party’s nomination just hours after President Joe Biden dropped out of his reelection bid on Sunday and endorsed her as his replacement. 

In a statement, Harris thanked Biden for his “decades of service to our country” and for his support as the party navigates new territory.

“I am honored to have the President’s endorsement and my intention is to earn and win this nomination,” she wrote. “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.”

After mounting pressure to elevate Harris and weeks of speculation after a poor debate performance in June, Biden announced on Sunday that he was finally stepping aside.

“My very first decision as the party nominee in 2020 was to pick Kamala Harris as my Vice President. And it’s been the best decision I’ve made. Today I want to offer my full support and endorsement for Kamala to be the nominee of our party this year,” Biden wrote on X, three days after former President Donald Trump accepted the Republican Party nomination.

The Congressional Black Caucus PAC, which had rallied behind Biden even when many were calling on him to step aside, immediately backed his decision to endorse Harris.

“She has been instrumental in delivering the accomplishments of the last 3.5 years and has led on lowering maternal mortality rates, protecting reproductive freedoms, and ensuring economic opportunities for all,” the group said in a statement.

U.S. Rep. Jim Clyburn of South Carolina, who saved Biden’s campaign in 2020, also threw his weight behind Harris.

“I am proud to follow his lead in support of her candidacy to succeed him as the Democratic Party’s 2024 nominee for President,” Clyburn said in a statement.

Some Black voters were equally enthusiastic about Biden’s major announcement.

“Harris has, as some folks would say, waited her turn,” Charleston, South Carolina, resident Kenya Cummings told Capital B. “I don’t see why she wouldn’t be a strong candidate.”

In the weeks after the debate, Democratic leaders, including former President Barack Obama, urged Biden to reconsider his bid, believing that his path to victory in November had significantly narrowed.

Black Americans had been some of the most steadfast champions of Biden’s reelection bid.

“The suggestion that any candidate who won their primary should simply step aside because victory appears difficult at the moment is disrespectful to the voters, unjust, and undemocratic,” more than 1,400 Black women wrote in a letter published last week criticizing the Democratic Party’s lack of unity.

Signatories included former Sen. Carol Moseley Braun of Illinois, who was the first Black woman elected to Congress’ upper chamber, and Keisha Lance Bottoms, the former mayor of Atlanta.

And Clyburn, toward the beginning of the month, voiced the sentiments of many other members of the CBC when he told reporters, “We’re ridin’ with Biden.”

Cummings, who is 35, noted that there was a meaningful generational divide when it came to Black support for Biden’s candidacy, saying that their parents believed that Black voters needed to “hunker down and back Biden” because he’s “our hope.”

Others echoed this general feeling of uncertainty.

“Well, right now, [Harris has] only been [a] sidekick,” 55-year-old Chicago resident Dorothy Holmes told Capital B. “Maybe she can do the job. Maybe she can’t. But she did run the other four years with [Biden] already.”

Can Harris really win? 

If Harris wins in November, she would be just the second Black U.S. president, after Obama, and the first woman president.

While Obama in a statement on Sunday lauded Biden’s legacy, he didn’t endorse Harris, focusing instead on the “uncharted waters” the party is in.

“I have extraordinary confidence that the leaders of our party will be able to create a process from which an outstanding nominee emerges,” Obama said.

Harris vied for the 2020 Democratic nomination, and made headlines during a June 2019 debate where she criticized Biden’s past efforts to find common ground with segregationists and his opposition in the 1970s to federally mandated school busing.

“There was a little girl in California who was part of the second class to integrate her public schools, and she was bused to school every day, and that little girl was me,” Harris said during the debate.

While that exchange instantly went viral — Harris’ campaign started selling “That Little Girl Was Me” T-shirts — the former U.S. senator from California also slammed into backlash.

“We can be proud of her nonetheless, but her ambition got it wrong about Joe,” Braun, who also rallied behind Biden in the 2020 contest, said at the time. “He is about the best there is; for her to take that tack is sad.”

Harris also faced attacks because of her history as a prosecutor: “Kamala is a cop” was a refrain and a meme among her detractors.

Still, Harris was a massive inspiration to many, particularly Black girls.

“It just feels like Black girls like me can run for class president, Black girls like me can go for the big things in life like she did,” then-14-year-old Paris Bond told CNN in 2020.

And Black women, often the backbone of the Democratic Party, continued to rally behind her and were among the first to publicly support the endorsement of Harris. 

U.S. Rep. Joyce Beatty of Ohio, a former head of the CBC, said thousands of Black women were trying to join a call Sunday evening in support of Harris’ presidential bid, a show of support for her campaign. The off-record mass call quickly reached capacity.

Earlier, Beatty told MSNBC: “For us, it’s personal and we stand with Vice President Harris.” Beatty led the CBC from 2021 until last year.

Georgia Democrat Stacey Abrams quickly pledged her support for Harris.

“She’s a tenacious fighter, a champion for our rights & defender of our democracy. United, she will lead us as we defeat Donald Trump this November. I am proud to endorse Vice President Kamala Harris as our Democratic nominee. Let’s go!”

The Washington Post averaged 11 post-debate polls and found that Harris and Biden stack up about the same against Trump.

While Biden has endorsed Harris, his delegates aren’t required to support her, though most Democrats strategists believe that she’ll become the party’s official nominee when delegates vote at the Democratic National Convention, which is slated to run Aug. 19-22.

Staff writer Adam Mahoney contributed to this report.

Brandon Tensley is Capital B's national politics reporter.