(Bloomberg) -- Kamala Harris staked her claim to top-tier status in the Democratic primary with a searing indictment of Joe Biden on race, putting the front-runner on defense and puncturing the aura of inevitability that he had carefully sought to cultivate.The deeply personal confrontation at a Democratic debate on Thursday pitted the 54-year-old daughter of Jamaican and Indian immigrants against a 76-year-old white man for fondly recalling his civil relationships with segregationist senators in the 1970s and 1980s. Both are aggressively courting the black community, a vital constituency that has decided the last five Democratic presidential nominees in every contested primary since 1992.For Harris, the exchange was her boldest gambit yet in making her personal identity and experiences a calling card — not Democratic socialism like Bernie Sanders, not policy papers like Elizabeth Warren, not optimism like Beto O’Rourke or Pete Buttigieg. Harris has struggled to catch fire, most notably with black voters, in part due to a lack of a clearly defined message as she sought to straddle the progressive and establishment wings of the Democratic Party. She attempted to change all that with the exchange with Biden.It is not yet clear if Harris can capitalize on this moment, or if she might succeed in dislodging Biden from his front-runner’s perch, only to see another candidate -- such as Warren -- slide into that position.Until now, Biden has dominated the crowded field with African American voters in early polls, boosted by universal name recognition, strong relationships with black leaders and eight years as Barack Obama’s vice president. That support has arguably been Biden’s biggest asset in the race, and Harris challenged it in the strongest terms of any Democrat so far in the contest, and on the largest stage.“I do not believe you are a racist,” she told him. “It’s personal, and it was hurtful to hear you talk about the reputations of two U.S. senators who built their reputations and career on segregation of race in this country. And it was not only that but you also worked with them to oppose busing.”Biden said Harris’ remark was a “mischaracterization” of his position, and that he “did not praise racists.” And in defending his past positions on busing, Biden went after Harris’ background as a prosecutor, something she has been criticized for in recent months.“I was a public defender,” Biden said. “I didn’t become a prosecutor. I came out and I left a good law firm to become a public defender when in fact my city was in flames because of the assassination of Dr. King.”The split-screen image of a black woman and an old-school Democrat was a reminder of how much the party has changed since Biden became a senator in 1973. A party once powered by white working-class Americans is increasingly made up of black and Latino voters, as well as young people and women. Biden may have an early lead, but the exchange with Harris revealed his growing demographic distance from the party.The generational divide was also raised by another one of the younger candidates, California Representative Eric Swalwell, 38, who used Biden’s own words to suggest that it was time for the vice president to step aside."Joe Biden was right when he said it was time to pass the torch to a new generation of Americans 32 years ago. He is still right today," Swalwell said.Biden brushed it off. "I’m still holding on to that torch," he said.Overall, the night did more to scramble than clarify the presidential race. Far from narrowing it to a two- or three-person contest, the two debates on Wednesday and Thursday revealed that five candidates still have a legitimate claim to being in the top tier — Biden, Harris, Sanders, Buttigieg as well as Warren, the only one of the five who debated on the first night. And even some of the lower-polling contenders like Swalwell and Michael Bennet showed a fighting spirit by taking shots at front-runners, an indication that they’re not ready to go quietly.Adrienne Elrod, an aide to Hillary Clinton’s 2016 campaign, said that the former vice president’s ties to the black community will not fade easily, despite Harris’s attack.“His support runs deep,” Elrod said.Biden’s pitch has included nostalgia for a time when Washington was less polarized between the two major parties, and on Thursday he pledged to “restore the backbone of America.”Louisiana Representative Cedric Richmond, a Biden supporter who is former chairman of the black caucus, said the former vice president “listened to Kamala Harris’s pain” in what he called an important exchange.He said the Biden’s record from the 1970s didn’t deter Obama from selecting him. “All of this was out there when the first African American president decided to pick Joe Biden as his running mate. And he had the vice president’s back every day of the week,” Richmond said.Harris, interviewed on Friday morning on MSNBC, was asked if she believed Biden was racially insensitive in a way that makes him unfit to be president.“I wouldn’t say that,” she said. “I just think he and I have a difference of opinion and also a difference of opinion on state’s rights.”Harris said in that interview she believes that the federal government sometimes needs to act when states don’t ensure civil rights protections, as in the case of busing or voting rights. “We have certain values that are national standards and we’re not going to let states compromise that,” she said.Sanders, who is runner-up in most polls but has slipped since his announcement, was the target of attacks from centrist contenders like John Hickenlooper and Bennet for his “Medicare for all” plan, which would largely end private insurance. The self-described democratic socialist held firm to his message of making health care a human right and expanding the safety net, but he repeatedly found himself on the defensive for the disruptive nature of his plans.The topic of race and policing began with a question for Buttigieg, who took time off the campaign trail after a white police officer killed a black man in South Bend, Indiana. Buttigieg admitted he had failed to diversify the police force, which is overwhelmingly white.Buttigieg drew praise from some Democratic operatives for admitting his failure in the aftermath of the shooting, but also for talking about issues in a way that weaved his personal background with policy proposals.But it was Harris who had the defining moment.Bakari Sellers, a former South Carolina state representative who endorsed Harris for president, said the California senator’s face-off with Biden was the “moment the campaign needed and wanted.”“One thing you can tell from that moment is she’s running to be president not anyone’s vice president,” he said. “At the end of the day, this is going to be a race. This is not a coronation of Joe Biden period. You can cancel the decorations for now. We’ve still got a primary to run.”(Updates with Harris interview from 19th paragraph.)\--With assistance from Jennifer Epstein.To contact the reporters on this story: Sahil Kapur in Miami at skapur39@bloomberg.net;Tyler Pager in Miami at tpager1@bloomberg.netTo contact the editors responsible for this story: Joe Sobczyk at jsobczyk@bloomberg.net, Max BerleyFor more articles like this, please visit us at bloomberg.com©2019 Bloomberg L.P.