Joe Biden emerged largely unscathed during a high-decibel debate Thursday night, turning in a surprisingly passionate performance and fending off a racially charged attack by Kamala Harris.

While Harris may have scored points among black voters, on balance the debate appeared to do little to dent Biden's front-runner status.

And led by Biden, the Democratic candidates denounced President Trump early and often, giving him a starring role and the second debate a confrontational and highly partisan edge. Within 40 minutes, some candidates were accusing him of kidnapping migrant children.

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The NBC moderators took a more aggressive approach out of the gate, compared to the undercard debate, as if they had been saving their ammunition for the main event. And unlike Wednesday night, they followed up when the candidates ducked.

Savannah Guthrie asked Biden about his remark that we “shouldn’t demonize the rich.” The former vice president pivoted to an attack on the president, saying “Donald Trump thinks Wall Street built America” and “has put us in a horrible situation” in terms of income inequality.

Guthrie went hard at Bernie Sanders, asking if he’d raise taxes on the middle class — he conceded that on the second try but said they’d save on health care — and then demanded to know whether “nominating a socialist would reelect Donald Trump.”

The senator said he beats Trump in the polls, unloading on him as a “phony,” “pathological liar” and “racist.”

Biden’s performance was punchier than many might have imagined by watching his more discursive style on the stump, neutralizing the “Sleepy Joe” label.

Biden had two highly emotional moments. On a question about ObamaCare, he spoke of health care by describing the death of his first wife and child in a car accident and the more recent death from cancer of his son Beau.

And on the border crisis, Biden talked about securing bipartisan funding for the border: “We all talk about these things — I did it.”

Pressed by Jose Diaz-Balart on the Obama administration’s deportation of 3 million illegal immigrants, Biden played defense but ultimately said those who don’t commit crimes shouldn’t be kicked out of the country.

Pete Buttigieg took a more moderate approach, saying he’s not for free college for everyone — and noting that he and his husband have a six-figure student debt — and even said it’s OK not to go to college. But his thoughtful approach was often overshadowed. The mayor gave an empathetic response to the fatal police shooting in South Bend, Ind., but was clearly on the defensive.

Kamala Harris seemed most energized when talking about the border, describing the desperation of a mother who hires a "coyote" to carry her child into unknown peril — and savaged Trump in the process.

But then came her pre-planned attack on Biden—and a possible breakthrough moment.

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The U.S. senator from California unloaded on Biden for having spoken fondly of working with segregationist senators. She slammed him for what she said was his opposition to busing. And Harris made it personal, describing how she was bussed to school as a young girl and every black man she knows has been racially profiled.

Biden fought back, in scattershot fashion at first. He denied ever praising the segregationists, which is true. He said he hadn’t opposed busing in the 1970s, just that imposed on communities by federal authorities. Biden grew stronger as he touted his own civil rights record.

The Biden-Harris dustup will be the story coming out of Miami, endlessly replayed and rehashed in news stories and cable segments. In that sense, it was a win for Kamala Harris, who catapulted herself into the spotlight while Sanders was busy defending socialism, and was the only candidate with the stones to attack Joe Biden. But he still leads the field by a substantial margin.