So much has been written about this past week’s two-day overhyped marathon Democratic presidential debate that it’s difficult to add anything new or original. We’re already seeing early data that reaffirms initial social media reactions about winners and losers, namely that Elizabeth Warren impressed on Wednesday, Kamala Harris dominated on Thursday, Julián Castro enhanced his profile a lot, Corey Booker enhanced his profile a little, and everyone would have been better off if NBC had audio problems whenever Chuck Todd asked a question.

But I think it is worth commenting on the exchange about race between Harris and Joe Biden, even though that may be the single most discussed moment of the four hours, because it goes directly to the issue of electability at the center of the Democratic primary campaign. The question keeping Democrats up at night is which candidate has the best chance to defeat Donald Trump next year. I will argue in my next post that this is an unknowable question, and it’s ill-advised to make assumptions about who the electorate may ultimately accept or reject.

But it is reasonable to work through the matter by assessing how candidates perform under the spotlight, and last Thursday, Harris took charge of the debate and never let go. When she unleashed her superb prosecutorial skills on Biden, she invited primary voters to imagine her doing the same on a debate stage a year from this fall. This, I believe, was the entire point of the exercise: to create a confrontation with the front-runner on her terms and force him either to defend himself or retreat, in the process inviting viewers to imagine her tearing into the president. When viewed from this perspective, Biden was merely a stand-in.

Biden’s claim to electability is his appeal to white working class voters in the Rust Belt and a longing to return to the normalcy of the Obama years (or as he has rebranded it, the Obama/Biden administration). This claim is bolstered by the deep well of affection many Democrats hold for Biden and his former boss, and on the assumption that Biden’s appeal and political experience make him the single best general election candidate at a moment when many Democrats are reluctant to take chances with a newcomer — in other words, the assumption that Biden will be able to handle Trump in a way that others cannot. Because this is an assumption, the success of the Biden campaign depends on demonstrating at every turn that it’s true. Anyone else who hopes to win the nomination has to undermine it.

On the debate stage last week, Harris blew it up.

She had no doubt observed Biden during the previous weeks and understood that his campaign has made a strategic choice not to apologize for his record. This of course mirrors the way Trump reacts all the time, meaning she could anticipate an engagement with Biden that would model what we might expect to see in the general election. Harris waited for her moment and attacked. “I do not believe you are a racist,” she told the frontrunner, before pivoting to her reaction to Biden’s statement earlier in the week about his ability to work with segregationist senators. This, she said, and his “work . . . with them to oppose busing” was “hurtful” and “personal” to her. Predictably, Biden became defensive about his record on civil rights instead of acknowledging Harris’ pain, playing into her hands by assuming the role Trump might play in a similar exchange. And the world was treated to a clinic on how Kamala Harris as the Democratic nominee would fillet the incumbent. 

Trump thrives on dominance and fear, and Harris demonstrated how to combat it by being fearless and taking command. She showed Democrats how to deploy prosecutorial tactics with surgical precision to force your opponent into a corner, pummel him when he’s down, and dominate the stage. Last Thursday, she forced Biden into a position where he was inexplicably defending his record with a states rights argument that was a favorite of segregationists. The usually mellifluous Veep was left struggling for words. He sounded angry and looked deflated. Now imagine how Trump would react if subjected to this type of humiliation at the hands of a woman of color. He would be so furious he might spontaneously combust.

One debate does not make or break a campaign, especially when that debate takes place almost a year and a half before election day. Biden went into the week the frontrunner and he is the frontrunner still. As much as Harris was the star on Thursday, so was Warren the star on Wednesday, demonstrating her own brand of strength and ability. Other candidates also acquitted themselves well and have time to make the case for their candidacies. But with Biden’s claim to the nomination built on his ability to win, his aura of inevitability will evaporate quickly if other candidates demonstrate that they are better able to get the job done.