The first half of March was not kind to Bernie Sanders. Following victories in Iowa, New Hampshire, and Nevada, he suffered disappointing defeats to Joe Biden on March 3 and March 10 and now trails in the overall delegate count. But as he faces off with Biden tonight in the primary’s first one-on-one debate, Sanders has a critical opportunity to turn everything around.

The United States, suddenly upended by a pandemic, is crying out for the type of drastic public health action that only Sanders promises to bring. This is his moment. In order to seize it, he must abandon the collegiality he’s shown Biden thus far and expose the former vice president for what he is: a feeble, confused, unelectable candidate whose platform is woefully insufficient to handle the crises we’re facing, much less defeat Donald Trump.

Sanders’s supporters seemed demoralized after his losses on Tuesday. Cable news was all but calling the race for Biden, and establishment hacks like James Carville and David Frum were openly calling for Sanders to drop from the race. Exit polls showed that while primary voters were more inclined to agree with Sanders on the issues, they overwhelmingly saw Biden as the more electable candidate. A question echoed over social media as a sort of resigned chorus: Does Bernie still have a chance?

But with a devastating coronavirus now sweeping the globe, threatening millions of Americans’ lives and livelihoods and exposing every glaring hole in our weak welfare state, a Sanders presidency suddenly feels more urgent than ever. He must be the nominee if we want any chance at recovering.

Single-payer health care, ridiculed for months by the media as too costly and too radical, is now being praised by CNN anchors as a reason other countries are better poised to contain the pandemic. And while in countries like Italy people are remaining at home and collecting paid leave, the Democratic establishment that Biden represents just caved to Republican demands and excluded 80 percent of American workers from receiving paid leave in their emergency legislation.

Sanders needs to tell debate viewers that Joe Biden not only opposes Medicare for All, but even said that he would veto it if it passed through the House and Senate due to its cost. With the government summoning $1.5 trillion (roughly the same amount in additional federal spending needed annually for Medicare for All) out of thin air on Thursday for a temporary Wall Street boost, Biden’s opposition looks absurd.

Sanders should demonstrate why his own policies are needed. But he also needs to be explicit about Biden’s countless flaws as a candidate, from his declining mental faculties to his indefensible political record to his terrible policy platform. Donald Trump is already attacking Biden on all of the above and seems poised to defeat him soundly in a general election.

Sanders can convince viewers tonight that he, not Biden, is the electable candidate. Recent general election polling backs this up, particularly in swing states, and with the nation waking up to the urgent need for his policies he can now make the case more strongly than ever. While he’s criticized Biden’s record more in recent weeks, he’s been reluctant to step up his attacks to the level needed. As Ruby Cramer reported in Buzzfeed , Sanders sees Biden as a friend and has disregarded advice from his staff to get more aggressive.

But it’s now or never. The gloves need to come off tonight.

It’s difficult to predict how the coronavirus pandemic will play out in the coming weeks and months. It will likely be devastating: doctors at a University of California, San Francisco panel devoted to the pandemic warned that our lives could be severely impacted for twelve to eighteen months and that over a million Americans may die. Millions more may lose their jobs, and indeed mass layoffs are already happening.

But what Sanders needs to make clear tonight is that pandemics don’t destroy societies — they reveal the ways in which societies are already broken.

The coronavirus is not going to cause the US health care system to fail — the system is already broken by design. The virus is not going to cause people to lose their incomes — it will expose the United States’ barbaric lack of paid leave and insufficient unemployment benefits.

And coronavirus won’t cause people to lose their homes — it will expose the United States as a country that already leaves people horrifyingly vulnerable to eviction, foreclosure, and homelessness. Put simply, people will soon notice in starker clarity than ever that the United States is a country designed to profit the rich while leaving the working class precarious and vulnerable.

This, in other words, is not a crisis with short-term solutions. We need to fundamentally rebuild the country’s welfare state as Sanders has spent decades calling for. Biden proudly promises a return to the Obama years, telling billionaires that “nothing will fundamentally change” if he’s elected and proposing a health care plan that will leave over ten million people completely uninsured. Sanders, on the other hand, promises bold, sweeping reforms with universal benefits that will guarantee security to Americans and build our societal resilience to future crises. It’s vital that he makes this contrast clear and tells tonight’s viewers that a Biden presidency (should he somehow defeat Trump) would leave all of our current vulnerabilities untouched.

This past week has felt like one of those in which decades happen. As horrible as this situation is, it’s a real opportunity for Sanders to seize control of this race and wake the public up to Biden’s serious deficiencies as a candidate. The country — the world — needs him to win if we are going to have any chance of going forward. These are the stakes, and this could be his final chance to turn the race around. It would be a crime to waste it by being too nice.