Harris, 55, was long considered the front-runner for the job. She is already known nationally and was tested on the campaign trail and in the media during her own presidential bid last year.
She also seemed to be an obvious fit for three key criteria that Biden publicly laid out for his running mate ― accomplished enough to be “ready to be president”, a similar mindset on key issues, and a woman.
The Democrats’ presumptive presidential nominee made clear early on that he was going to pick a woman, and as the racial justice protests picked up over the summer, he was under increased pressure to choose a Black woman.
“I have the great honor to announce that I’ve picked @KamalaHarris — a fearless fighter for the little guy, and one of the country’s finest public servants — as my running mate,” Biden said on Twitter.
I have the great honor to announce that I’ve picked @KamalaHarris — a fearless fighter for the little guy, and one of the country’s finest public servants — as my running mate.
— Joe Biden (@JoeBiden) August 11, 2020
Even before then, Biden and his team recognised the value of having a Black woman on the ticket. Pundits were writing off his presidential bid after his poor showings in the predominantly white states of Iowa and New Hampshire. But then South Carolina, whose Democratic Party is largely powered by Black voters, delivered an overwhelming victory to Biden, turning around his campaign.
If elected, Harris would be the first Black and first female vice president in U.S. history.
Charismatic and youthful compared to the 77-year-old former vice president, Harris will also provide something of a contrast to Biden.
She had attracted national attention and was considered a rising star as attorney general of California, even before her election to the Senate in 2016.
Biden’s pick for his running mate is particularly important due to his age. If elected, he would be the oldest president ever at the time of inauguration. During the primary, Politico reported that Biden had signaled he might seek only one term, although he subsequently said he had no such plan.
Being chosen for the vice presidential slot immediately makes Harris a leader of the Democratic Party and a likely front-runner for the nomination after Biden.
The two grew close during his time as vice president, due to her working relationship with his son Beau, who died in 2015. Harris and the younger Biden served as state attorneys general at the same time.
Biden had made clear that he wanted a running mate who was “simpatico with me philosophically.”
“Agrees with me. Now if you’re not, that’s OK, I have great respect,” he said in August 2019. “But you’ve got to be able to turn and say to your vice president, ‘This is your responsibility.’ Because the job is too big anymore for any one man or woman.”
Harris dropped her presidential bid in December after her campaign failed to bring in enough money. At the time, Biden said that he deeply respected the senator and that she could “be the president one day herself.”
In early March, Harris endorsed the former vice president’s bid, saying there was “no one better prepared than Joe to steer our nation through these turbulent times and restore truth, honor, and decency to the Oval Office.”
But Harris and Biden also had one of the most memorable arguments during the primary debates.
During the first Democratic debates in June of last year, Harris challenged Biden over his praise of segregationist senators’ “civility” ― which she called “very hurtful” ― and his opposition to busing in the 1970s.
“There was a little girl in California who was a part of the second class to integrate her public schools and she was bused to school every day,” she told him. “And that little girl was me.”
The moment was biting. Biden performed poorly during the debate, raising questions about his ability to handle the pressures of the campaign and whether many of his old positions were too out-of-step for the current party. It also stung for Biden, who didn’t expect Harris to go after him so aggressively because of her relationship with his late son.
“I was prepared for them to come after me, but I wasn’t prepared for the person coming at me the way she came at me,” Biden told CNN after the debate. “She knew Beau. She knows me.”
This article originally appeared on HuffPost UK and has been updated.