Former Vice President Joe Biden on Friday tried to clarify his position on enforcing school desegregation through busing a day after he was criticized for his response to Sen. Kamala Harris, who confronted him over the issue at the first Democratic presidential debate.

"I'd like to say something about the debate we had last night, and I heard and I listened to, and I respect, Senator Harris," Biden said at the Rainbow PUSH Coalition convention in Chicago. "But we all know that 30 seconds to 60 seconds on a campaign debate exchange cannot do justice to a lifetime committed to civil rights."

"I want to be absolutely clear about my record and position on racial justice, including busing," Biden said. "I never, never, never, ever opposed voluntary busing, as a program that Senator Harris participated in and that made a difference in her life."

Biden has faced mounting criticism in recent weeks for his comments about working with lawmakers who supported segregation and opposed civil rights during his early years as a senator.

Harris, a California Democrat, confronted Biden over the remarks in a fiery exchange Thursday night in which she discussed the racism she had to endure as a child, including when she was bused to an all-white school.

“It was hurtful,” Harris, the only black candidate on the stage, said in reference to Biden's comments about his relationship with former Sens. James Eastland, D-Miss., and Herman Talmadge, D-Ga., who were segregationists.

“I do not believe you are a racist,” Harris told Biden before criticizing the former Delaware senator for his reminiscence about working with senators who she said "built their reputations and career on the segregation of race in this country.”

Biden fired back, saying Harris had “mischaracterized” his position “across the board.”

On Friday, Biden continued to try to defend his record on civil rights and race.

"I have always been in favor of using federal authority to overcome state-initiated segregation," he said. "In fact, I cast a deciding vote in 1974 against the amendment called the Gurney Amendment, which would have banned the right of the federal courts from using busing as a remedy. ... It wasn't what you'd call the most popular vote in the country at the time."

In the 1970s and early 1980s, however, Biden worked with a faction of Southern senators — Republicans and Democrats — to block the use of federal funds to enforce desegregation through busing. He also supported a 1975 amendment that effectively would have preserved segregated classrooms by prohibiting the federal government from using funds as leverage to force integration.