Sen. Kamala Harris on Thursday had the strongest performance in two nights of Democratic debates — and it wasn't even close.

Harris commanded the stage, gave consistently strong answers, and won the most important exchange of the campaign season by eviscerating Joe Biden on his past opposition to school busing and fond remembrance of his working relationship with segregationists.

She was a clear winner.

Harris had a strong moment early on when candidates were shouting at each other when it was her time to speak and she said that Americans didn't want to see a food fight but wanted to know how they were going to put food on their table.

The line itself was cheesy and obviously rehearsed, but what was important was that everybody else hushed after she said it and she took control of the floor. It established her early on as the leader on the stage.

She was able to speak substantively and passionately on climate policy, immigration, economic issues, and guns in ways that resonated with the audience — sustaining her high energy from the start of the debate to the end.

And then, there was the highlight of the debate, one that we may look back at as historic, which is when she confronted Biden.

It should be said that the moment was not handed to her: She seized on a conversation about race to say that as the only person of color on stage, she deserved a shot to chime in.

She spoke about the discrimination she and her family faced growing up, then smoothly pivoted to a devastating attack on Biden, which she delivered firmly yet respectfully.

“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.”

Harris spoke about how she herself benefited from school busing as a little girl in California.

Biden's response was weak. He tried to discuss his record on civil rights and how his opposition was to the Department of Education forcing busing on local communities.

But that answer was not going to fly with a large swathe of the Democratic Party in 2019, and Harris was quick to point out that the federal government had to step in in other instances when states were trampling on civil rights.

Eventually, Biden in attempting to counter Harris, cut himself off, noting "my time's up." That came across as him throwing in the towel, especially given we know Biden typically loves to hear himself talk.

Biden also seemed unprepared to answer an obvious question later in the debate on his vote for the Iraq War.

Overall, Biden came off as old and tired, as if he was trying to coast through the debate.

Harris came with a clear plan, was well prepared, and executed perfectly. The fact that she was willing to take on Biden, the front-runner, signaled that she was the alpha on the stage.

It's hard to know how much these early debates will affect poll numbers. But going into the debate, Harris seemed to have been losing steam after her strong roll-out, as other candidates, particularly South Bend, Indiana, Mayor Pete Buttigieg and Sen. Elizabeth Warren, gained ground. Tonight, she looked like somebody you could easily imagine addressing the Democratic convention as the nominee next summer.