MIAMI — Former Vice President Joe Biden was forced to defend his record on desegregation in the 1970s under grilling from Sen. Kamala Harris of California — the only black candidate on the Democratic debate stage Thursday night. The intense exchange came less than two weeks after Biden came under harsh criticism for boasting about his ability to form personal relationships in past decades with race-baiting former Sens. James Eastland, D-Miss., and Herman Talmadge, D-Ga.

“It was hurtful,” Harris said, to hear Biden speak of his bonds with those senators. She told the story of a little girl who was in an early wave of children to integrate schools in California, ending the anecdote with these words: “That little girl was me.”

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In the 1970s and early 1980s, Biden led a Southern bloc of Republican and Democratic senators who blocked the use of federal funds to enforce desegregation through busing. Biden also wrote an amendment in 1975 that would have had the effect of protecting segregated classrooms within schools by prohibiting the federal government from using its funds as leverage to force integration.

Biden’s amendment was adopted by the Senate but killed in the House.

“I do not believe you are a racist,” Harris said, but she took umbrage at his willingness to associate himself with Eastland and Talmadge, “who built their reputations and career on the segregation of race in this country.”

And she questioned Biden’s contention that he didn’t agree with them.

“You also worked with them to oppose busing,” she said.

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

"I did not oppose busing in America,” he said, and suggested that he opposed busing that was mandated by the federal government, but would not have opposed locally imposed busing. He claimed that Harris wouldn’t have been affected by his amendments.

“The fact is that in terms of busing, you would have been able to go to school because it was a local decision made by your city council,” Biden said.

Pulling back, the argument Biden made in the 1970s — and again on Thursday — is that the role of the federal government in integrating schools should have been limited, leaving power to school districts to make those calls.

Harris, hinting at the generations-long battle between federal and state powers, noted that not all states would have integrated schools without federal intervention.

“There are moments in history where states failed to protect the rights of all people,” she said.

Biden had his own barb for Harris, noting that he had worked as a public defender, while she was a prosecutor. But Harris seemed to have gotten the better of the exchange, more passionate and seemingly more prepared for combat than he was.

A few moments later, mid-sentence, Biden stopped himself.

“My time is up,” he said. “I’m sorry.”