(CNN) Joe Biden has named Kamala Harris as his running mate, making the California senator the first Black and South Asian American woman to run on a major political party's presidential ticket.
"I've decided that Kamala Harris is the best person to help me take this fight to Trump and Mike Pence and then to lead this nation starting in January 2021," the presumptive Democratic presidential nominee wrote in an email Tuesday.
The two are set to appear together for the first time for a speech Wednesday in Wilmington, Delaware. Biden's campaign has not yet said what time that speech will take place.
In selecting Harris, Biden adds to the Democratic ticket a former primary rival who centered her own presidential bid on her readiness to take on Donald Trump and show Americans she would fight for them. She rose to national prominence within the Democratic Party by interrogating Trump nominees during Senate hearings, from former Attorney General Jeff Sessions to Supreme Court Justice Brett Kavanaugh.
Harris' selection comes months after Biden committed to picking a woman to join him on the Democratic ticket. Harris, 55, is now the third woman to serve as a vice presidential candidate for a major political party, following Geraldine Ferraro as the Democratic vice presidential pick in 1984 and Sarah Palin as the Republican vice presidential pick in 2008.
Aware that his age could be a concern to some voters, Biden, 77, has said that he is "a bridge" to a new slate of Democratic leaders, and by selecting Harris, more than 20 years his junior, he has elevated a leading figure from a younger generation within the party.
Trump told reporters after news of Harris' selection broke that she was "my number one draft pick" as a potential Biden running mate. Trump pointed to her criticism of Biden's past positions on busing to desegregate schools in a June 2019 Democratic debate.
"She was very disrespectful to Joe Biden and it's hard to pick somebody that's that disrespectful," Trump said.
Biden's selection unfolded with the utmost secrecy after a period in which he spoke with the contenders either in person or in face-to-face meetings. He notified several close advisers on Tuesday, two people familiar with the matter told CNN. After considering some 11 women for the post, he and his aides spent time on Tuesday afternoon notifying the vice presidential prospects who he did not choose.
His calls included California Rep. Karen Bass, the chairwoman of the Congressional Black Caucus, as well as Georgia Democrat Stacey Abrams, Illinois Sen. Tammy Duckworth, Massachusetts Sen. Elizabeth Warren, New Mexico Gov. Michelle Lujan Grisham and Florida Rep. Val Demings, sources familiar with the matter told CNN.
As part of the selection process, the former vice president spoke directly to the final contenders, according to people familiar with the process, through either face-to-face meetings or remote conversations. Officials would not say which of the candidates visited Biden in person, but CNN confirmed last week that Michigan Gov. Gretchen Whitmer had flown to Delaware for a meeting. Harris and former Obama national security adviser Susan Rice were among the others seen as the most serious contenders.
CNN had previously reported that Biden was also believed to be considering Bass, Sen. Elizabeth Warren of Massachusetts and Sen. Tammy Duckworth of Illinois, people familiar with the search say.
In another sign that the pick was imminent, a Biden campaign official told CNN on Tuesday that they have assembled the staff for Biden's future running mate.
Karine Jean-Pierre, who joined the Biden campaign as a senior adviser in May, will lead the Harris' team as chief of staff. Jean-Pierre had previously worked for Barack Obama and Martin O'Malley's presidential campaigns.
Two veterans of the Obama-Biden administration are also joining the team. Liz Allen, who served as deputy communications director for Biden as vice president as well as deputy communications director in the White House, is joining as communications director to Harris. And Sheila Nix, who was chief of staff to Biden's reelection campaign in 2012 and served as Jill Biden's chief of staff in the White House, will be a senior adviser to Harris and her husband, Douglas Emhoff. The vice presidential pick is expected to also add a few of her own advisers to the team.
The last time Biden and Harris shared the stage was March 9 in Michigan, the eve of a primary that would prove decisive in Biden's primary battle. On a stage in a Detroit high school gymnasium, Biden gestured to Harris, Whitmer and New Jersey Sen. Cory Booker and called himself a "bridge" to "an entire generation of leaders" within the Democratic Party.
The spouses of Biden and Harris, Jill Biden and Emhoff, had an exchange over Twitter as Biden welcomed Harris to the ticket.
"Hey @DouglasEmhoff Are you ready?" Jill Biden tweeted.
"America, let's do this!" Emhoff said.
Progressives also quickly welcomed Harris to the Democratic ticket. Vermont Sen. Bernie Sanders tweeted that Harris "will make history as our next Vice President."
"She understands what it takes to stand up for working people, fight for health care for all and take down the most corrupt administration in history. Let's get to work and win," he said.
Harris started out in the vice presidential search process as a favorite because of her experience as a senator, California attorney general and district attorney in San Francisco and her extensive vetting as a presidential candidate. Ultimately, she was chosen by Joe Biden the "common sense pick" who everybody could agree would "do no harm," a source familiar with the vetting process told CNN.
With her multi-racial background as the child of two immigrants to the United States, her allies believed she could complement Biden as a symbol of a changing America.
She also proved to be a hardworking surrogate for Biden in recent months, taking part in everything from virtual policy events with voters in swing districts to a live DJ dance party fundraiser with Diplo and D-Nice online.
When Trump tweeted about delaying the election in late July, she responded on Twitter by saying he is "terrified" because "he knows he's going to lose to @JoeBiden. It will require every single one of us to make that happen."
Still, some members of Biden's team resisted choosing Harris. A recent Politico story noted that former Sen. Chris Dodd of Connecticut, who was helping vet candidates, was still galled by her attack on Biden during a June 2019 debate in Miami, when she criticized his work with segregationist senators and highlighted his fight against busing to desegregate schools decades ago.
The pushback against Harris apparently became so strong that Biden felt the need to defend her during his July 28 press conference, where an Associated Press photo captured the talking points about her on his notecard that included "do not hold grudges" and "great help to campaign."
Harris also benefited from being a running mate who could match this turbulent moment in American history.
Many of the issues at the center of her life's work -- including criminal justice reform, improving health care for Black Americans and tackling income inequality -- have come to the forefront in the three-pronged crisis America is now facing: the coronavirus pandemic (which has disproportionately affected communities of color), the fight against systemic racism and an economic recession.
The protests against police brutality of Black people in the wake of George Floyd's death also gave Harris an opening to more succinctly explain her decision to become a prosecutor as a young lawyer, despite the deep mistrust of that profession among Black Americans who have been wronged by the criminal justice system.
During the recent "Live Free" forum, the California senator was asked what she says to activists and voters who contend that as attorney general, she was part of the system and don't trust her to be part of the change within it.
Harris said she grew up experiencing some of the abuses of the system, noting that every Black man she knows has experienced "some form of profiling, of excessive force, of unreasonable stop or seizure."
She noted that she made a very conscious decision to become a prosecutor: "I said why do we only have to be on the outside, trying to knock down doors to change the system? ... Isn't there a role for us to go inside the system and try to change it?"
She pointed to aspects of her record as California's attorney general that she said were incremental steps toward police reform: arguing that she "opened up California's data system" to assist activists who were trying to "claw that information out" through public records requests -- making data around deaths, custody and arrest rates by race more accessible.
Harris also highlighted her work improving re-entry initiatives for the formerly incarcerated, and a program that required implicit racial bias and procedural justice training for law enforcement officers under her command when she was California's attorney general.
"These are just a few of the things that we were able to accomplish, certainly not enough, which is why I keep working on it. It has been my life's work to keep working on this and I'm not going to stop," she said.
As the half-Jamaican, half-Indian-American daughter of immigrants who sought higher education in the United States, Harris and her sister Maya Harris grew up steeped in the world of academia and the Black intellectual circles of Oakland and Berkeley, California.
Harris' mother, Shyamala Gopalan Harris, a breast cancer specialist who pursued her graduate studies at UC-Berkeley, and her father, Donald Harris, who became an economics professor at Stanford, both protested during the Civil Rights Movement, giving Harris what she has called "a stroller-eye view" of activism from a very young age.
She attended Howard University in Washington, DC, a place that taught students, she has said, "that we could be anything -- that we were young, gifted, and Black, and we shouldn't let anything get in the way of our success."
After graduating from UC-Hastings College of the Law, she prosecuted child sexual assault, robbery, homicide and three strikes cases in the courtrooms of Alameda County and San Francisco.
One of her proudest achievements was her work as California attorney general pursuing predatory lenders after the financial crash of 2008 and her decision to hold out for a larger settlement from the big banks for Californians after the foreclosure crisis.
The banks initially offered what she has referred to as crumbs on the table, she held out for what become a $20 billion settlement, relishing the chance to take on the top officials at the big banks who "seemed to be under the misimpression that I could be bullied into submission."
She has often described the shouting match that ensued when she decided to directly dial Jamie Dimon, the then-chairman and CEO of JPMorgan Chase -- how she took off her earrings because of "the Oakland in me" and yelled at one another "like dogs in a fight," she wrote in her memoir "The Truths We Hold."
Harris has also written at length about being repeatedly underestimated as a political candidate. One political strategist told her there was no way she could win, according to her memoir, "because I was 'a woman running for attorney general, a woman who is a minority, a woman who is a minority who is anti-death penalty who is DA of wacky San Francisco.' Old stereotypes die hard." (Ultimately, she edged out her Republican opponent in a race so close it took weeks to tally the ballots.)
As California's junior senator, she has championed immigration issues, including the cause of the so-called "Dreamers" who were brought to America as young children.
She created viral moments as a senator by demonstrating her prosecutorial demeanor when Trump nominees came before the Senate Judiciary Committee that elevated her profile within the Democratic Party.
When she entered the 2020 presidential race in January 2019, Harris appeared to be a formidable contender, but like many others, she struggled to maintain a position at the top of the polls within a crowded field of candidates.
Fundraising, as well as power struggles within her campaign -- which was directed in part by her sister Maya, the campaign chairwoman -- proved to be difficult hurdles to overcome. In a last-ditch effort to revive her bid, the campaign decided to go "all in" on Iowa in September, then slashed staff and redeployed aides in October from New Hampshire, California and Nevada to the Hawkeye State.
Aides had privately questioned the campaign's abrupt shifts in strategy, Harris' swerving message and a lack of clear leadership at the top.
The moment that captured the most attention during her presidential bid was also the one that injected the most uncertainty into her ability to rebuild a strong working relationship with Biden.
As rivals, Biden and Harris had been on friendly terms in part because of her friendship with Biden's late son, Beau; the two met when they served as attorneys general together, she from California and he from Delaware.
But during that Miami debate, Biden looked stunned when Harris delivered her unexpectedly harsh blow by noting that she had been one of the children who benefited from busing. The moment went viral and she shot up in the polls. But her strong standing did not last -- and Biden and his wife Jill were both clearly blind-sighted by what Biden allies perceived as a vicious and opportunistic attack.
Harris has tried to mend those relationships in the months since her departure from the presidential race as she has campaigned with Biden and joined forces with Jill Biden to highlight issues like Black maternal mortality.
"You're a role model to women and girls across this country, including my granddaughters, and it's no secret that you and our son Beau worked closely together and shared a special connection," Jill Biden said to Harris during a recent virtual event with Milwaukee voters that focused on the threats to the Affordable Care Act.
In that same event, Harris demonstrated the fierceness she has often shown when taking on Trump. She called out the President's decision to once again ask the Supreme Court to strike down the ACA at a time when so many Americans face have lost their insurance due to layoffs and tens of thousands are dealing with new pre-existing conditions after contracting the coronavirus
"People are dying," Harris said. "But Donald Trump is prioritizing his political prospects and playing games."
During a recent appearance on NBC's "Late Night with Seth Meyers," Harris said she would do anything to get Biden elected.
"We need to save the soul of our country, we really do," she said. "We need a president who cares about the people and loves the people."
This is a breaking news story and will be updated.