Kamala Harris tells ABC's Robin Roberts she credits Biden with 'audacious' pick of woman of color VP

In an exclusive interview with ABC News, former Vice President Joe Biden spoke about the important recommendation that helped him choose California Sen. Kamala Harris to join him on the Democratic ticket as his vice presidential nominee.

“She had the best recommendation she can get: my son Beau, not a joke,” Biden told “Good Morning America” co-anchor Robin Roberts during the interview conducted Friday in Wilmington, Delaware.

Biden recalled his son, who died from an aggressive form of brain cancer in 2015, requesting that the then-vice president make the trip to California to nominate Harris for her Senate seat during the state’s Democratic convention in 2016 -- a sign of their close bond.

“They were good friends and Beau had great respect for Kamala, knew she was tough. She has a backbone like a ramrod. She's completely, thoroughly honest,” Biden said. “So it was easy for me, it was easy for me.”

Roberts and "World News Tonight" anchor David Muir conducted joint interviews with Harris and Biden's joint interview -- their first since accepting the Democratic nomination -- which was featured in a special edition of "20/20" called "The Ticket: The First Interview," which aired Sunday on ABC.

Harris’ nomination for the second-highest position in the United States is historic: She is the first woman of color, and the first Asian American to be nominated for vice president. Harris praised Biden for his bold decision.

“Joe, in selecting a woman of color, a woman of color to be his vice president -- what an audacious move. The audacity of Joe Biden to actually just make that decision, and then follow through on it. And in that way, advance something that might have taken many, many, many years otherwise,” Harris told Roberts.

“That's one of the things that really makes me so respect and have affection for Joe Biden, because those are the kinds of things he does, and he doesn't seek permission to do it. He doesn't look to whether or not it’s popular. He said I'm going to select a woman, and then he selected a woman of color. Right? It says a lot,” she continued.