Washington (CNN) New Jersey Sen. Cory Booker took issue with Joe Biden's answer during Thursday night's Democratic presidential debate when the former vice president defended his decades-old position against busing to desegregate schools during his tenure as a first-term US senator.

"That struck me. I literally leaned back in my couch and couldn't believe that one moment to me, and again not understanding the history of the need for the federal government," Booker, who watched fellow Democratic presidential contenders duke it out from his Washington, DC, home, told CNN's John Berman on "New Day" Friday morning.

Booker said "anybody who knows our painful history" knows that African-Americans "have had to turn to the federal government to intervene because there were states that were violating those rights."

"There were states and state policies that were driving these deep divisions in our country," Booker argued.

Booker, who was on the 2020 Democratic debate stage Wednesday night, told CNN that whoever is the Democratic nominee will have to be able to talk about racial issues in America in an "open and honest and even vulnerable way."

"If they make mistakes, if they say something wrong, as we all do, they can't fall into a defensive crouch and shift blame, they have to be able to help our country heal and reconcile," he said on "New Day."

"I did not oppose busing in America. What I opposed is busing ordered by the Department of Education, that's what I opposed," Biden said.

Biden also insisted that he "did not praise racists" when he earlier this month pointed to two segregationist senators as examples of colleagues he could work at a time when there was "some civility" in the Senate.

"I was in a caucus with James O. Eastland. He never called me 'boy,' he always called me 'son,'" Biden said at a fundraiser earlier this month, referring to the Mississippi senator who spoke of black people as "an inferior race."

"When you dredge up sort of words like, 'Hey, they didn't call me boy, they called me son' and not understand the history and the hurt that that kind of degrading language has, I think that we have to have a nominee that's up to this challenge, and I think that we're going to see whether or not Joe Biden is," Booker told CNN's "New Day" Friday.

"I don't think you can fault folks like me for calling him out if he fails to live up to the standard that our next nominee should have and speak to the real pain and the real hurt that I think Kamala spoke to last night," he continued.

Kamala Harris takes Joe Biden to task

The former prosecutor commanded the debate stage Thursday night, challenging Biden over his record of working with former colleagues who were segregationists and busing.

"Vice President Biden, I do not believe you are a racist, and I agree with you, when you commit yourself to the importance of finding common ground," Harris said. "But I also believe -- and it's personal -- it was actually hurtful to hear you talk about the reputations of two United States senators who built their reputations and career on the segregation of race in this country."

As Biden stared straight ahead, looking somewhat pained, Harris continued by criticizing the former vice president for trying to prevent the Department of Education from enforcing school busing to integrate schools during the 1970s, noting that decision hurt a little girl in California.

"That little girl was me," Harris said with emotion swelling in her voice. "So I will tell you that on this subject, it cannot be an intellectual debate among Democrats. We have to take it seriously. We have to act swiftly."

Biden called it a mischaracterization of his record "across the board."

The two Democratic presidential candidates -- Booker and Biden -- have clashed over Biden's remarks on the segregationist senators

Following Biden's comments, Booker called on the former vice president to apologize in a sharp rebuke.

Biden, in turn, suggested that Booker should apologize. "He knows better. There's not a racist bone in my body. I've been involved in civil rights my whole career," Biden argued.