Sen.Kamala Harris (D-Calif.) sharply criticized former Vice PresidentJoe Biden’s record on racial segregation in a dramatic, bracing exchange that marked the defining moment of the Democratic primary debate on Thursday night. Harris broke into a conversation about race among the other candidates by pointing out she was the only black person onstage. She recounted discrimination she experienced growing up, then turned to Biden, who earlier this monthfondly recalledcollaborating with two segregationist senators during his Senate career. “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 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.”

WATCH: Harris says she doesn't think Biden is a racist, but she talks directly to Biden about his having worked with segregationists on the issue of school busing. #DemDebate2pic.twitter.com/Ytb2xvOhux — NBC News (@NBCNews) June 28, 2019

Biden’s remarks had previously sparked rebukes from Harris and Sen. Cory Booker (D-N.J.), presenting perhaps the sharpest disagreement in the Democratic primary so far. Speaking of former segregationist Sens. James Eastland (D-Miss.) and Herman Talmadge (D-Ga.), Biden said at a New York fundraiser that “at least there was some civility” and “we got things done.” On Thursday night, Harris made it personal, connecting Biden’s opposition to busing programs that integrated schools to her own experience attending public schools as a child. “There was little girl in California who was part of the second class to integrate her public schools, and she was bused to school every day,” she said. “And that little girl was me.” Harris’ campaign tweeted a photo of her as a child with a version of the same quote.

There was a little girl in California who was bussed to school. That little girl was me. #DemDebatepic.twitter.com/XKm2xP1MDH — Kamala Harris (@KamalaHarris) June 28, 2019

As a young senator in the early 1970s, Biden worked to oppose federal initiatives to use busing to integrate public schools in an effort to overcome decades of schooling and housing discrimination across the United States. Biden said Harris had mischaracterized his career. “I did not praise racists,” he said. Biden invoked his record on civil rights issues and said he became a public defender when his city was in flames because of the assassination of Dr. Martin Luther King. “I ran because of civil rights. I continue to think we have to make fundamental changes in civil rights,” Biden said.

ASSOCIATED PRESS Former Vice President Joe Biden, Sen. Bernie Sanders (I-Vt.) and Sen. Kamala Harris (D-Calif.) at the Democratic primary debate Thursday night.