MIAMI--Former Vice President Joe Biden’s campaign defended the 2020 hopeful Thursday night after his heated exchange with Kamala Harris following the controversy over his comments on segregationist senators, saying his civil rights record is “unassailable.”

From the spin room at the Adrienne Arsht Performing Arts Center after the debate, Biden communications director Kate Bedingfield, senior adviser Symone Sanders, and surrogate Anita Dunn defended Biden’s response to Harris’ criticisms.

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“If you want to put Vice President Biden’s record on civil rights up against anybody else on that stage, he’ll stand the test of time,” Sanders told reporters Thursday night.

“What voters want to hear is what kind of president he’s going to be and how he’s going to tackle these issues in the White House, and I think his record on civil rights is unassailable,” Bedingfield added.

Their defense of Biden came after what was perhaps the most heated moment of the debate Thursday night. Harris, D-Calif., told Biden that she doesn’t believe he is a “racist,” but considered his recent comments about being able to work with segregationist senators early in his career “hurtful.” (Biden has said he disagreed with the senators on segregation but was still able to work with them in the Senate.)

“You worked with them to oppose busing,” Harris then said, referring to efforts to limit orders for school desegregation by busing. In an emotional moment, she told her own story of being bussed as a little girl in California.

Biden fired back that Harris’ comments were a “mischaracterization of my position across the board,” saying he never praised racists while denying that he opposed busing. He insisted that he opposed busing ordered by the Department of Education, as opposed to localities making their own decisions.

“A suggestion that Joe Biden is against school integration is frankly just ludicrous,” Bedingfield said Thursday night, adding that the former vice president planned not to “engage in personal back and forths.”

“Look, he is the frontrunner, people are going to take swings at him, trying to create a moment, trying to score their points—it’s a debate,” Bedingfield said. “He heard her story, I think she told it very powerfully. He listened. I think you heard him focus on his message for the American people and what he would do as president.”

Sanders added that critics were “looking for Vice President Biden to comment on Sen. Harris’ experience.”

“Her experience is her experience and I think we should leave it at that,” Sanders said. “I think the question is, is he someone that folks can trust on education, is he someone that communities of color can trust? I would say yes.”

On MSNBC late Thursday night, Harris was asked whether she thought Biden’s White House bid was “done” after their quarrel on the debate stage. She responded: “No, I don’t think so.”

“Listen, Vice President Biden has had a long career of dedicated public service, and he has done great things in his career, and I think he should be given credit for those things and for that work and for his dedication,” Harris said on Chris Matthews. “I don’t think anyone can question his reason for doing what he does. I do believe that he cares about people, and he loves our country. So I don’t think he’s done, no.”

Meanwhile, the campaign also defended Biden over criticisms about his age. Rep. Eric Swalwell, D-Calif., 38, took a shot at Biden, 76, on the debate stage Thursday night, calling on him to “pass the torch” to a new generation of Americans.

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“He is still as enthusiastic and excited about the possibilities of the American future as he was when he was first elected to the Senate at the age of 29,” Dunn told reporters. “He still carries a torch for the future of America and for what this country should be and for raising the middle class and for those who aspire to be in the middle class. It is what has emanated his career, and it is what continues to emanate his career.”

She added: “I think anyone who was tuning in to say ‘oh is there a problem here?’ saw an energetic, enthusiastic, and frankly someone who is carrying the torch for the future.”

Fox News’ Alex Pappas and Judson Berger contributed to this report.