The clash was immediately heralded as a breakout moment for Harris and a moment of glaring weakness for Biden. Harris’ team clearly prepared for the attack, with social media posts highlighting her comment jumping on to Twitter and Instagram within minutes. They also waited for this moment ― while Sen. Cory Booker (D-N.J.), who participated in Wednesday night’s debate, sharply attacked Biden for his comments last week, the Harris campaign clearly decided to hold its firepower until a moment of maximum impact. Harris’ performance likely guarantees a spike in online fundraising and media attention in the coming weeks.

“I did not oppose busing in America,” he said. “What I opposed is busing ordered by the Department of Education.”

Biden defended himself, calling Harris’ statement “a mischaracterization of my position across the board” and arguing he was fighting against federal interference in local matters, not against busing per se.

It was not only the most vivid confrontation of either debate between two candidates in the top tier, it also touched on the racial fault lines where Biden may be the most vulnerable within the Democratic Party and where the conversation is most heated in American society.

“You also worked with them to oppose busing. And, you know, there was a little girl in California who was a part of the second class to integrate her public schools, and she was bused to school every day,” Harris told Biden at the beginning of the debate’s second hour. “And that little girl was me.”

The brief exchange, in terms of the news cycle, will essentially erase everything that came before and after it during the debate, along with everything that happened in the first Democratic debate on Wednesday night.

For much of America ― the portion that doesn’t eagerly consume political news more than 16 months before a general election ― Thursday night’s two-hour Democratic presidential primary debate in Miami will be cut down to a single moment, YouTube clip, television news segment or newspaper headline: Sen. Kamala Harris ’ confrontation of former Vice President Joe Biden over his history of working with segregationist senators to oppose busing to desegregate public schools.

Wilfredo Lee/ASSOCIATED PRESS Former Vice President Joe Biden may have stood at the center of the debate stage on Thursday night, but it was Sen. Kamala Harris of California who will be the center of attention afterward.

But before writing an early political obituary for Biden’s third presidential run, it’s worth remembering that Biden is betting the Democratic Party hasn’t changed nearly as much as everyone thinks. He’s aiming at an older generation of voters, both black and white, and those voters so far have been more than willing to forgive his past mistakes. How these voters react to Harris’ high-profile attack will determine how far, if at all, Biden falls from his perch atop the Democratic primary polls.

Biden’s Other Problems

But Harris’ attack wasn’t the only moment to expose a potential Biden weakness. Early on, 38-year-old Rep. Eric Swalwell (D-Calif.) noted that the former senator had delivered a speech decades ago in which he called on politicians to “pass the torch” to a younger generation.

In this case, Biden handled it well ― denying a lower-tier candidate a chance to grab attention by slashing at a front-runner. “I’m still holding on to that torch,” Biden said before quickly pivoting to talk about his plans to improve the education system.

Another attack, this one from Sen. Michael Bennet (D-Colo.), went directly at one of Biden’s supposed strengths: his ability to work with Republicans. Bennet criticized a deal Biden struck with Senate Majority Leader Mitch McConnell to avoid the so-called “fiscal cliff” in 2012 and noted he was one of just three Democratic senators to vote against it.

“The deal that he talked about with Mitch McConnell was a complete victory for the tea party,” Bennet said. (At the time, Bennet said he opposed it because it didn’t adequately address the national debt.)

Biden’s only response before the moderators moved on? “Oh, come on.”

Biden had several other curious statements. The National Rifle Association is one of the largest villains in Democratic politics, outside of President Donald Trump. Biden declared the NRA wasn’t the enemy but the gun manufacturers were. And when asked what his first act as president would be, Biden declared it would be to defeat Trump. While he probably intended this as a statement about his strength against Trump in public polling, it was more than a bit confusing.

Overall, Biden did little to emphasize his strengths while several moments highlighted potential weaknesses. And at the end of his exchange with Harris, he uttered a phrase you would expect him to avoid at all costs: “My time is up, I’m sorry.”

Sanders Is Sidelined But Gets His Message In

Sen. Bernie Sanders (I-Vt.) and his economic proposals seemed to dominate discussion early in the debate as he sparred with former Colorado Gov. John Hickenlooper and Sen. Kirsten Gillibrand (D-N.Y.) over “socialism” and whether embracing far-left proposals would hurt Democrats in the general election. Sanders hit his regular notes about economic inequality and accused Trump of lying to his supporters.

But Sanders, the 2016 Democratic primary runner-up, seemed to fade into the background Thursday as attention quickly shifted to Biden and his fiery exchanges with other candidates. Though the senator stood in a prime location on stage ― between Biden and Harris, the other two top-ranked candidates in the race ― Sanders never got in a major exchange with either. It was similar to how Sen. Elizabeth Warren (D-Mass.), another top-tier progressive, dominated the early stages of Wednesday night’s debate but faded as other candidates began to clash.

Sanders, when confronted with a question about his electability, also got a chance to hammer home a point his campaign has been making for months: He’s leading Trump in polls. “The last poll I saw had us 10 points ahead of Donald Trump because the American people understand that Trump is a phony,” he said.

In fact, Sanders actually came to Biden’s defense on stage immediately after the debate in an interview with a reporter. The 77-year-old senator decried “ageism” (a reference to Swalwell suggesting that Biden should “pass the torch”) and also complained about the “45-second” answer period allotted to each candidate.

Democrats Remember Trump Is The President

One of the biggest differences between the candidates who appeared on stage in Miami on Wednesday night versus the candidates who sparred there on Thursday was their focus on Trump. On Wednesday, the candidates hardly mentioned the president. Most of that night’s most memorable moments involved splits within the Democratic Party and various policy proposals. Warren, for instance, never mentioned the president.

But Trump dominated the debate on Thursday. In fact, there seemed to be more mentions of the president in the first 10 minutes than in the entire two hours on Wednesday.

“Look,” Biden began early in the night. “Donald Trump has put us in a horrible situation.”

Sanders quickly joined in, promising to “expose Donald Trump for the fraud that he is.”

And Harris followed soon after by dismissing a question about free college with a call to repeal the tax cuts Trump signed into law in 2017.

“Where was that question when the Republicans and Donald Trump passed a tax bill that benefits the top 1% and the biggest corporations in this country?” she said to applause.

The Moderators Skipped Ahead To The General Election

Before the debates, the Progressive Change Institute released a study of what voters at the presidential candidates’ town hall events had quizzed candidates about. Much of the data was unsurprising: Health care, immigration and the environment were top topics. But it was also clear what Democratic primary voters didn’t care about: Less than 1% of the questions were about how a candidate would pay for one of their plans.

But in the early moments of both debates, NBC’s moderators asked the candidates how they planned to pay for their ambitious agendas. While swing voters may eventually care about how exactly Warren will pay for her plan to eliminate student debt (with a 2% tax on wealth over $50 million), it’s fairly clear that rank-and-file Democratic primary voters don’t at the moment.

And other questions were framed more around the fears of Republicans than the aspirations or plans of Democrats. A question about gun control was framed around fears of gun confiscation ― a step no Democrat on stage supported, though Swalwell said he supports a mandatory buyback of assault weapons. Former Housing Secretary Julian Castro was asked Wednesday if he supported “open borders.”

Meanwhile, climate change ― which Democrats typically rate as one of the three most important issues, along with gun control and health care, went unmentioned in both debates until the final half-hour.