There were only two candidates on stage at Wednesday night’s Democratic debate who really mattered: Joe Biden, the front-runner, and Kamala Harris, who’d skewered Biden in the first debate and was polling within striking distance in some early states. No one else on stage was hitting 2 percent in the national polling average. With that in mind, the takeaway is clear: Harris lost, and Biden won.

Harris’s troubles began with her lackluster opening statement, a recitation of some lines from her stump speech on the theme that “we are better than this.” Her worst moments occurred shortly thereafter, during the debate over health care, which revealed her substantive weakness on the policy issue dominating the Democratic primary.

Biden landed some solid blows against Harris’s health-care plan by pointing out that it doesn’t take effect for ten years, would cost $30 trillion over a decade once implemented, would eventually abolish employer-based insurance, and would require “middle-class taxes to go up, not down.”

“Anytime someone tells you you’re going to get something good in ten years, you should wonder why it takes ten years,” Biden said. “This is the single most important issue facing the public. And to be very blunt and to be very straightforward, you can’t beat President Trump with double-talk on this plan.”

And “double-talk” is what Harris ultimately engaged in when discussing the cost of her plan.

Colorado senator Michael Bennet also pointed out that Harris’s plan abolishes employer-based insurance and costs $30 trillion, adding that this price tag equals 70 percent of all federal revenues over the next decade. “We cannot keep with the Republican talking points on this,” Harris responded.

Biden claimed his own plan establishing a “public option” would cost $750 billion (one-fortieth the cost of Medicare for All), limit co-pays to $1,000, and cap out-of-pocket health-care expenditures at 8.5 percent of income.

“$30 trillion has to ultimately be paid,” Biden said. “I don’t know what math you do in California, but I tell ya, that’s a lot of money, and there will be a deductible. The deductible will be out of your paycheck, because that’s what will be required.”

“Let’s talk about math!” Harris replied. “Let’s talk about the fact that the pharmaceutical companies and the insurance companies last year alone profited $72 billion, and that is on the backs of American families.” What Harris didn’t note is that if every dollar of that $72 billion were confiscated, it would pay for about 2.4 percent of one year of her plan. That’s probably why she began denouncing Biden’s plan as “immoral” for failing to sufficiently rein in insurance companies, rather than actually talk about math.

Harris deftly attacked Biden on the issue of busing during the first debate, but the issue didn’t work for her on Wednesday.

“Vice President Biden says that your current position on busing, you’re opposed to federally mandated busing, that that position is the same as his position. Is he right?” CNN moderator Jake Tapper asked.

“That is simply false,” Harris said. But Harris failed to explain how her position on busing differs from Biden’s position today — something she has been struggling to do for the past month — and instead said that she would have voted differently back in the 1970s.

Biden did something smart during his rebuttal: Rather than relitigate the 1970s, he pivoted to an attack on Harris’s record in California. He criticized her for failing to bring any cases as California attorney general to desegregate the San Francisco and Los Angeles public schools, and he went after Harris for failing to provide potentially exculpatory evidence to prisoners that ultimately resulted in 1,000 of them being freed. “If you doubt me, Google 1,000 prisoners freed, Kamala Harris,” Biden said.

The Sacramento Bee reports: “Biden alluded to a crime lab scandal that involved her office and resulted in more than 1,000 drug cases being dismissed. [Representative Tulsi] Gabbard claimed Harris ‘blocked evidence that would have freed an innocent man from death row until she was forced to do so.’ Both of these statements are accurate.”

Biden also appeared, in contrast to his first-debate performance, lucid and sharp when debating Cory Booker on the issue of criminal justice and Julián Castro on the issue of immigration.

“I have guts enough to say his plan doesn’t make sense,” Biden said of Castro’s plan to decriminalize illegal entry into the United States, a policy backed by most other Democratic candidates. “When people cross the border illegally, it is illegal to do it unless they’re seeking asylum. People should have to get in line. That’s the problem. And the only reason this particular part of the law is being abused is because of Donald Trump. We should defeat Donald Trump and end this practice.”

Biden did have a few moments of weakness. He refused to say whether he’d advised President Obama to stop deportations — “I keep my recommendation to him in private” — but later touted his private recommendation to Obama against the troop surge in Afghanistan. And just when it looked like Biden was in the clear, he appeared to struggle to read a teleprompter or cue card when he haltingly concluded his closing remarks by telling debate watchers to “go to joe-3-0-3-3-0 and help me in this fight.” There was no joe30330.com website to visit. Biden had apparently garbled a message about texting “joe” to the number 30330.

But all in all, it was a good night for the septuagenarian front-runner. Whether he can keep it up when all of his serious rivals — Elizabeth Warren, Bernie Sanders, and Kamala Harris — are on the same stage is a question to be answered at the next debate, in September.