“Back when Kamala was Attorney General, she worked closely with Beau,” he added, referring to his late son who was Delaware’s chief law enforcement officer while Harris held the same post in California. “I watched as they took on the big banks, lifted up working people, and protected women and kids from abuse. I was proud then, and I’m proud now to have her as my partner in this campaign.”

The pair will speak in Wilmington, Delaware on Wednesday before attending a virtual grassroots fundraiser.

Tuesday’s long-awaited announcement was lauded by supporters, such as former President Bill Clinton.

“This is a terrific choice! @KamalaHarris will be a great partner and she and @JoeBiden make a strong team,” Clinton tweeted.

Obama administration national security adviser Susan Rice and California Rep. Karen Bass, who themselves were in contention for the job, offered their hearty congratulations.

Joe Biden’s wife, the former second lady Jill Biden, welcomed Harris’ husband Douglas Emhoff to the fall fight.

“Hey @DouglasEmhoff. Are you ready?” she tweeted.

Emhoff replied: “Ready to work! Let’s go @DrBiden!”

Harris, 55, was a former California attorney general, San Francisco district attorney, and Alameda County line prosecutor before she launched her own White House campaign in January 2019 to comparisons with former President Barack Obama.

Born to a Jamaican father and Indian mother, Harris surged in polling and fundraising following the opening primary debates in June after she confronted Joe Biden for touting his work with segregationists during his 36-year Senate career representing Delaware and for opposing federally mandated busing in the 1960s and 1970s. But she failed to capitalize on that momentum last summer.

Their fiery debate exchange led to doubts that she would become his running mate, but the pair repaired their frayed relationship.

“I’m so lucky to have you as part of this, this partnership going forward,” Biden told Harris at an April fundraiser. “We can make a great deal of difference, and the biggest thing we can do is make Donald Trump a one-term president.”

He continued, “So, I’m coming for you, kid.”

Biden’s selection of Harris as his understudy comes after the civil unrest provoked by George Floyd’s death on May 25 under the knee of a white police officer. The treatment of Floyd, a black man, amplified calls for a minority woman to be on November’s ticket.

Harris will likely encounter the same challenges ahead of the general election as she did during the primary before she dropped out in December. While the member of the Senate Judiciary and Intelligence committees rose to national prominence for her incisive questioning of then-Supreme Court nominee Brett Kavanaugh, her bid was hindered by inconsistent performances on the campaign trail. She also struggled to counter criticism regarding contradictions in her prosecutorial record and her positions on policies such as “Medicare for all.”

President Trump’s campaign has already launched attacks their way, claiming Harris is proof Biden “is an empty shell being filled with the extreme agenda of the radicals on the left.”

“Not long ago, Kamala Harris called Joe Biden a racist and asked for an apology she never received,” Trump spokeswoman Katrina Pierson said in a statement. “Clearly, Phony Kamala will abandon her own morals, as well as try to bury her record as a prosecutor, in order to appease the anti-police extremists controlling the Democrat Party. In her failed attempt at running for president, Kamala Harris gleefully embraced the left’s radical manifesto, calling for trillions of dollars in new taxes and backing Bernie Sanders’ government takeover of healthcare.”

Biden, 77, was repeatedly pressed by the media and voters alike on the qualities that he was looking for in a second-in-command, given his age. He reportedly told allies he’d only be a one-term president as well. In response, he said that he was searching for someone who was “simpatico” with him on issues and ready to lead at a moment’s notice.