Transcript for Joe Biden picks Kamala Harris as running mate
Good evening and it's great to have you with us here on a very busy Tuesday night. And we begin here tonight with the news that broke late today. The historic decision from former vice president Joe Biden, revealing today senator kamala Harris was his choice for a running mate. The campaign posting this image of Biden at his home in Delaware today, in a zoom chat with Harris, asking her to join him on the ticket. If elected, she would be the first woman vice president, the first African-American vice president, she would be the highest ranking asian-american in U.S. History. In a statement, Biden called Harris smart, tough and ready to lead, saying she'll be the best partner in the battle for the soul of this nation. News of Biden's choice spread across quite, in fact, what they call a heat map right here late today. I shows where the eat thes were most concentrated when the news was announced. Tonight here, who is kamala Harris? Her childhood, her firsts, the history she's made already. And what about all of that talk about senator Harris took aim at Biden on the debate stage? And the former vice president himself and his own notes on kamala Harris in recent days, captured in a photo, in his own writing, writing "Do not hold grudges." And tonight, president trump, just moments ago, weighing in on this pick. ABC's Mary Bruce leading us off. Reporter: Tonight, for the first time in our nation's history, a black woman is on the ticket. After weeks of speculation, Joe Biden this afternoon over video chat informing senator kamala Harris of his historic decision. Biden then tweeting the news -- "I have the great honor to announce that I've picked kamala Harris -- a fearless fighter for the little guy, and one of the country's finest public servants -- as my running mate." Harris responding -- "Joe Biden can unify the American people because he's spent his life fighting for us. And as president, he'll build an America that lives up to our ideals. I'm honored to join him as our party's nominee for vice president, and do what it takes to make him our commander in chief." Biden has said he was looking for someone he could trust. To be the last person in the room giving him advice. I think the most important thing is choosing the vice president is whether or not the person is simpatico with me in terms of where I want to take the country. Reporter: Biden and Harris have a personal family connection, first meeting through Biden's late son beau, when he and Harris were both state attorneys general. Four years later, after beau Biden died from brain cancer, Harris saying, "I still miss him." But Harris would become a rival. There was a little girl in California who was part of the second class to integrate her public schools, and she was bussed to school every day. And that little girl was me. Reporter: At the first primary debate, taking the former vice president to task for working with segregationist senators to oppose school bussing policies in the 1970s. It's a mischaracterization, my position across the board. I did not praise racists. That is not true. Do you agree today that you were wrong to oppose bussing in America then? Do you agree? I did not oppose bussing in America. What I opposed is bussing ordered by the department of that's what I opposed. Reporter: Harris later reportedly said that wassal politics. Biden clearly willing to look at a press conference two weeks ago, one of the first public signs Biden was leaning towards Harris. Photographers getting a glimpse of his talking points about Harris. Right on top, "Do not hold grudges." In this moment of racial reckoning, and after black voters helped save his candidacy, Biden was under intense pressure to pick a black woman. Tonight, the other women reacting. Former U.N. Ambassador Susan rice calling Harris a "Tenacious and trailblazing leader." Senator Elizabeth Warren saying Harris has been "Unafraid and an inspiration to millions of women who see themselves in her." And from congresswoman Val demings, a powerful reflection, saying, "To see a black woman nominated for the first time reaffirms my faith that in America, there is a place for every person to succeed no matter who they are or where they come from." Hillary Clinton weighing in with this message to another women making history, "I'm thrilled to welcome kamala Harris to a historic democratic ticket. She's already proven herself to be an incredible public servant and leader. And I know she'll be a strong partner to Joe Biden. Please join me in having her back and getting her elected." And president Obama tonight writing, "Joe Biden nailed this decision. By choosing senator kamala Harris as America's next vice president, he's underscored his own judgment and character." Even before Biden announced his decision, the trump campaign warned they would try to paint Biden's pick as a radical. Just moments ago, the president himself attacking Harris. Plus she was very, very nasty to -- one of the reasons it surprised me, she was very -- she was probably nastier than even pocahontas to Joe Biden. She was very disrespectful to Joe Biden. And it's hard to pick somebody that's that disrespectful. When she said things during the debates, during the Democrat primary debates that were horrible about sleepy Joe. And I would think that he would not have picked her. Reporter: But it was Biden earlier this year who said just what he would be looking for in a nominee. It's incredibly presumptuous for me at this stage to be talking about a running mate, I'll get killed if I get specific. But let me tell you what, rather than who. I'd very much like my administration to look like the country, like Barack and our administration looked like. Black, brown, women, men, gay, straight. Across the board, to look like the country. As vice president, I think it will be wonderful to have a woman or a person of color as vice president. But the most important thing I've learned from my relationship with Barack, I call him Barack, not president, because I don't want to confuse him with the president. But at any rate, one of the things I learned is that no president in the 21st century can handle the job all by themselves. It's just too much that lands on your plate. So you've got to be prepared to turn over significant responsibility as the president did with me on matters relating to a whole range of issues, and turn it over and run it from beginning to end. The vice president on what he would like to see in a vice president during the campaign. And let's get to Mary Bruce tonight. And Mary, I know we expect former vice president Joe Biden and senator kamala Harris to appear together tomorrow. All this playing out during this pandemic, which is why we saw that zoom call today. Any more on how this will look tomorrow? Reporter: Well, David, for the first time tomorrow, we will be seeing the harris/biden ticket together. They are set to deliver remarks in Biden's hometown in Delaware. Harris will then have just a week to prepare for the democratic convention, but she has been laying the groundwork for this for her entire career. Tonight, sources close to Harris say they are overcome with emotion, one telling us, now, onto the hard part. David? Mary Bruce leading us off tonight. Mary, thank you.
This transcript has been automatically generated and may not be 100% accurate.