California Sen. Kamala Harris launched a coordinated attack on former Vice President Joe Biden on Thursday, arguing that her very presence on the 2020 debate stage was in spite of, and not because of, Biden’s record in the U.S. Senate.

After an hour of policy talk, Harris, the only African-American candidate on stage, went after Biden’s long record on racial issues and opposition to federal funding for interracial busing in the U.S. Senate.

“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 I also believe, and it’s personal, and it was actually very 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. And it was not only that but you also worked with them to oppose busing.”

She then recounted her experience as a student in Berkeley, California.

“There was a little girl in California who was part of the second class to integrate her public schools and she was bused to schools every day, and that little girl was me. Vice President Biden, do agree today, do you agree today that you were wrong to oppose busing in America then? Do you agree?” Harris asked.

Biden went on defense, arguing that local governments had the right at the time to oppose it.

“I did not oppose busing in America,” Biden said. “What I opposed is busing ordered by the Department of Education. That’s what I opposed.”

And in 2019, Harris had a tweet ready to go, suggesting that the line of attack on Biden was pre-planned.

The clash only amounted to about three minutes of the two-hour spectacle, but it encapsulated arguments about the 76-year-old frontrunner’s age and long legislative record that went largely unmentioned for nearly four hours of TV time by 19 other Democratic candidates.

The four leading 2020 candidates in Thursday’s debate also split into two distinct groups on healthcare policy and free college, clashing over ideas more than personalities while presenting their plans to overhaul the nation’s healthcare and education systems.

Biden and Pete Buttigieg, mayor of South Bend, Indiana, backed an expansion of Obamacare while letting private health insurance companies continue to operate. Harris and Vermont Senator Bernie Sanders said private health insurance will not exist if they are elected to office.

“I mean that healthcare in my view is a human right, and we’ve got to pass a Medicare for All single-payer system,” Sanders said. “Under that system, by the way, the vast majority of people in the country will be paying significantly less for healthcare than they are now.”

Biden said the quickest and fastest way to build up consumer confidence in the nation’s healthcare system is to expand Obamacare.

“I’m against any Democrat who wants to take down Obamacare and any Republican,” Biden said, after referencing his family’s health-related tragedies. “Urgency matters, there’s people right now facing what I faced.”

Buttigieg also went personal when discussing his position against making college free for everyone, even though he and his husband accrued significant student debt.

“So college affordability is personal for us,” Buttigieg said. “Chasten and I have six-figure student debt. I believe in reducing student debt. It’s logical to me that, if you can refinance your house, you ought to be able to refinance your student debt. I also believe in free college for low and middle-income students for whom cost could be a barrier.”

The split between the leading candidates presents a clear contrast to voters with Biden and Buttigieg representing a step-by-step vision for change while Sanders and Harris argued for greater change. Buttigieg and Biden also backed incremental changes to lower the costs of attending college while Sanders touted his plan to provide free college for everyone, regardless of degree or income level.

The astronomical costs of Sanders’ plans led the self-described democratic socialist to embrace an idea that was considered political suicide for years: raising taxes for middle class Americans.

“People who have healthcare on Medicare for All will have no premiums, no deductibles, no co-payments or out-of-pocket expenses,” Sanders said. “Yes, they will pay more taxes but less in healthcare for what they get.”

South Florida is home to some of the highest rates of Obamacare enrollment in the country. Local lawmakers wary of the political fallout of embracing socialism and anxiety among constituents who currently benefit from Obamacare are in Biden and Buttigieg’s camp.

Colorado Gov. John Hickenlooper, who was booed for bashing socialism at a recent campaign stop in California, argued that Harris’ and Sanders’ healthcare positions will make it harder for whoever the Democratic nominee is to beat Donald Trump, especially in crucial states like Florida, Pennsylvania, Michigan and Wisconsin.

“If we turn towards socialism we run the risk of reelecting the worst president in American history,” Hickenlooper said. “I think that the bottom line is, if we don’t clearly define that we are not socialists, the Republicans are going to come at us every way they can and call us socialists.”

Harris and Sanders, who rank second and fourth among 2020 candidates in the polls, were the only two candidates on stage to back abolishing private insurance. Sen. Elizabeth Warren and New York City Mayor Bill de Blasio backed the idea on Wednesday night.

“Everybody who says they’re for Medicare for All, every person in politics who allows that phrase to escape their lips has a responsibility to explain how we’re supposed to get from here to there,” Buttigieg said. “Here’s what I want to do. It’s very similar. I would call it Medicare for All for those who want it.”