Updated at 4:57 p.m. ET

Former Vice President Joe Biden is defending his civil rights record after a rough Democratic debate Thursday night where California Sen. Kamala Harris blasted him over his past opposition to federally mandated busing.

"I heard and I listened to and I respect Sen. Harris. But you know we all know that 30 seconds to 60 seconds on a campaign debate exchange can't do justice to a lifetime committed to civil rights," Biden told the Rainbow PUSH Coalition, founded by the Rev. Jesse Jackson, in Chicago. "I want to be absolutely clear about my record and position on racial justice, including busing. I never, never, never ever opposed voluntary busing."

The black community has historically strongly supported Biden.

"Y'all are the ones that brung me to the dance," he told the group of African American and labor leaders. But while jovial at times, his pushback underscores how important black voters are to the Democratic primary; it's a critical coalition that Harris is trying to flip to her side, beginning in earnest Thursday night.

After more than 40 years in public life, Biden's record before he became the vice president to the country's first black president is getting renewed scrutiny.

The longtime former Delaware senator argued he had long worked to address the "root causes" of education inequality for blacks and whites, including working to desegregate neighborhoods. He touted his support for extending the Voting Rights Act, along with his opposition to an amendment that would have effectively banned busing, which "wasn't the most popular vote in the country at the time."

"These rights are not up to the states to decide," Biden said. "They're our federal government's duty to decide. It's a constitutional question to protect the rights of every single American, and that's always been my position."

"I know I've fought my hardest to ensure [that] voting rights, civil rights are enforced everywhere," Biden emphasized.

Harris, the only black woman in the Democratic contest, swiped hard at Biden during Thursday's debate in one of the most memorable and tense moments of the evening, not just over his approach to busing but over other recent comments about his "civil" working relationship with segregationist lawmakers in the Senate.

"It was 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," Harris said. "And it was not only that — you also worked with them to oppose busing."

She then described how growing up in California she was bused to integrate her public schools.

"And that little girl was me. 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," Harris said.

Biden retorted that he "did not oppose busing in America" but "busing ordered by the Department of Education." He said Harris' criticisms were "a mischaracterization of my position across the board."

On Friday, however, Biden tried to focus on what he described as Trump's indifference toward growing racial violence. Biden also touted his eight years of service in the Obama administration.

"My president gets much too little credit for all he did," Biden said about the 44th president. "I'm tried of hearing about what he didn't do. This man had a backbone like a ramrod."

As for Trump, Biden said he has "yet to apologize or criticize the Ku Klux Klan and the white nationalists," pointing specifically to the president's controversial equivocation after a rally involving white supremacists in Charlottesville, Va., in 2017. Trump said that there were "some very fine people on both sides," after a violent clash of protesters.

The Washington Post investigated Biden's past stances on busing earlier this year, finding that in the mid-1970s he was in fact resistant to busing as a solution as racial tensions were escalating back in his home of Wilmington, Del. The Postreports Biden took "a lead role in the fight, speaking out repeatedly and forcefully against sending white children to majority-black schools and black children to majority-white schools. He played down the persistence of overt racism and suggested that the government should have a limited role in integration."

In 1975, Biden told a Delaware newspaper, "I do not buy the concept, popular in the '60s, which said, 'We have suppressed the black man for 300 years and the white man is now far ahead in the race for everything our society offers. In order to even the score, we must now give the black man a head start, or even hold the white man back, to even the race.' I don't buy that."

Friday morning, Jackson told CNN that Biden's stance in the '70s "was on the wrong side of history." He said Harris was "on point" with her comments.

Still, at his organization's event Friday afternoon, Jackson — a civil rights leader who marched with the Rev. Martin Luther King Jr. and ran twice for president himself — introduced Biden.

"You have the stuff that it takes to make America better," he said.

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