Evan Vucci / AP

About 30 minutes into tonight’s Democratic debate, former Vice President Joe Biden made an assertion that summed up the entire marathon primary season.

“People are looking for results, not a revolution,” Biden said.

He was arguing against the Medicare for All plan that has dominated so many previous Democratic debates, a policy proposal that represented the central dividing line among the many candidates who once fought for the nomination. Now the race is down to just two—Biden and the author of that proposal, Senator Bernie Sanders of Vermont. And the debate over Medicare for All—indeed, the whole campaign—is occurring in a dramatically new context, as the nation responds to the rapidly spreading novel coronavirus that has already infected more than 3,000 Americans and threatens to overwhelm health-care systems across the country.

The ripple effects of the outbreak of COVID-19, the disease caused by the coronavirus, were visible from the moment Biden and Sanders took the stage tonight. A debate planned for Arizona had been stripped of its live audience and moved to CNN’s studio in Washington, D.C. The two podiums were set a Centers for Disease Control and Prevention–approved six feet apart, and upon entering the set, Biden initiated an elbow bump with a sheepishly smiling Sanders instead of the traditional handshake.

Biden is pitching himself as the candidate of stability, the tested veteran who can handle a crisis more ably than the Republicans’ erratic incumbent, President Donald Trump. Answering the expected questions of how he would respond to the pandemic, Biden leaned on the Obama administration’s response to the Ebola outbreak. He’d call a meeting in the Situation Room, ramp up testing, build hospital capacity, and push for a “major, major, major bailout package” geared toward helping workers, not corporations. The focus was on immediacy, the here and now. Biden promised to “listen to the experts.”

Sanders talked about all of that too. But he used the crisis as an opportunity—perhaps his last one—to advocate for the revolutionary change that has defined his two campaigns for the presidency. The pandemic, he said, “exposes the dysfunctionality of the health-care system and how poorly prepared we are despite how much money we spend.”

Responding to Biden’s caution against a revolution, he said, “It is not good enough not to be understanding how we got here and where we want to go into the future.”

“God willing, this crisis is going to end,” Sanders continued. “And we’re going to have to develop an economy in which half of our people are not living paycheck to paycheck and struggling to put food on the table.”

Biden scoffed at Sanders’s suggestion that Medicare for All would have made the nation better able to handle a pandemic, because people would not hesitate to go to the doctor out of fear that they would not be able to pay for treatment. “With all due respect for Medicare for All, you have a single-payer system in Italy. It doesn’t work there,” Biden said. “It has nothing to do with Medicare for All. That would not solve the problem at all.”

The two men bickered bitterly at times, dashing the hopes of some Democratic leaders that Biden’s lead and the coronavirus crisis would prompt Sanders to hold back in a spirit of unity. Sanders unloaded on Biden’s record in the Senate, bringing up his votes on bankruptcy bills and his comments years ago suggesting that he supported cuts to Social Security and Medicare. Biden occasionally struggled to respond, and an exasperated Sanders implored viewers to go to “the YouTube” to fact-check his rival’s memory.

Biden tried repeatedly to steer the conversation away from policy nitty-gritty. “This is a national crisis. I don’t want to get into a back-and-forth in terms of our politics here,” he said.

He wanted to look beyond Sanders, to project a presidential image and turn to the coming campaign against Trump. To that end, he called for the president to mobilize the military to aid in the domestic response to the coronavirus, and he later pledged to nominate a woman as his vice president.

Yet the big question hanging over Biden and Sanders tonight was: Will an unprecedented public-health crisis make voters more or less resistant to systemic change?

It’s a debate Biden has been winning handily of late, as the initial weeks of the COVID-19 outbreak have coincided with his racking up a significant, potentially insurmountable delegate lead over Sanders. The former vice president had a breakout night on Super Tuesday and coasted to double-digit wins over the Vermont senator last week in Michigan, Missouri, and Mississippi. Biden is heavily favored in the three delegate-rich states that vote on Tuesday: Florida, Ohio, and Illinois.

Sanders tonight made clear that he would not go quietly, that he would make at least one more aggressive push against Biden and for his much more transformative progressive agenda. He succeeded at many points tonight, just as he did in 2016 and for the past year across the country. But it might not be enough.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.