For the past three years U.S. citizens, and indeed all living beings on earth, have been besieged by the plague that is Donald Trump and the Republican party that has become his wholly-owned subsidiary.

Trump has made war on science, journalism, the welfare state, and constitutional democracy. He has made a mockery of public service and he has poisoned public discourse. He has enriched the financial elite along with his kleptocratic family and friends, bestowing on the adulating mobs who follow him a little bread and a lot of circus.

Trump has destroyed the public service-providing agencies of the state and turned precarity into a principle.

And now, as we face an existential crisis caused by a truly global pandemic, he lies, dithers, dissimulates, and places everyone and everything at risk.

Only public health can save us. And only public action can save public health.

The Democratic primary, having winnowed down to a two-person contest, has been overshadowed and reshaped by the coronavirus, which has caused a cessation of conventional campaigning and has reframed public discourse.

At the same time, the current moment represents a real opportunity for the contest to move forward. Because Trump is proving himself so manifestly unfit to hold public office. And because both Bernie Sanders and Joe Biden are proving to be so manifestly superior to Trump, as policy advocates, as human beings, and as political leaders.

The day after Trump presented a bumbling Oval Office “address,” both Sanders and Biden made powerful speeches saying what needs to be said: that the Trump administration is failing in a way that endangers us all; and that the American people need a vigorous response to the pandemic spearheaded by a real leader.

Both Sanders and Biden were statesmanlike. Both indeed gestured toward the kind of Congressional bipartisanship that is necessary, if anything is going to get accomplished right — for the pandemic won’t wait until November. At the same time, both strongly attacked the record of the Trump administration, advocated for major public policy changes, and exemplified what well-informed leadership looks like.

Biden’s speech was more moderate, and more “Presidential” — having spent eight years around the White House, and having performed some major public duties in his role as Vice-President, Biden truly inhabits the role with comfort and relative ease, something that is important, especially in a crisis.

Sanders’s speech was more radical — and in my view, more inspiring. Like all of his campaign speeches, it was buoyed by a powerful rhetoric of social justice and a well-articulated public policy agenda, centered, of course, on “health care as a human right,” and on Medicare for All as the instrument of this right.

If there ever was a time in which this message rings true, it is right now — when a universal system of testing and care is mandated by the simple requirements of survival, and where the inability of any sick people to obtain or afford testing and care is harmful not only to them and their families, but to everyone in their vicinity and thus to everyone.

Biden and Sanders represent different currents within the Democratic party. Both seem to understand that only a strong and unified effort can defeat Trump. While the nominee has obviously not yet been chosen, it seems very clear that it will almost certainly be Biden, something acknowledged by many prominent left writers, some of whom, like Jamelle Bouie, have been strong Sanders supporters.

Indeed, Sanders himself seems to understand this, even as he legitimately continues to press Biden to incorporate his agenda and his base.

I have been greatly impressed by the way both men, who do appear to be friends, have stepped forward in the face of the current health crisis.

I have also been impressed by a third individual who has stepped forward in a major way to explain the current crisis and the ways it might best be addressed: Ron Klain.

Klain has been ubiquitous in recent days. His expert testimony this week before Congress was carried live on C-Span. He has been a guest on virtually every MSNBC hourly show, and was featured on a particularly long and informative, segment of “The Rachel Maddow Show.” And he gave a widely-read interview for New York Magazine criticizing the Trump’s administration’s malfeasance, and explaining clearly how any normal President would have handled the crisis.

Klain is a smart man. And everyone is talking to and about him for a reason: because he served in 2014-15 as the Ebola Response Coordinator (“the Ebola Czar”) during the Obama Administration’s successful effort to stem the tide of that epidemic (and also to reassure the American public that it was up to the task).

Klain is a long-time Democratic operative, and if there is a Democratic “establishment,” he is a member in good standing. He served as chief of staff to Vice President Joe Biden, and before that served as chief of staff to Vice President Al Gore. He is an experienced Washington policymaker. He currently serves as Executive Vice President and General Counsel of Revolution LLC, an investment firm. He is also major figure in the inner circle of Biden campaign advisers that have long had close ties to the former Vice President, and he is most certainly someone who would hold a top post — perhaps White House Chief of Staff — in a Biden administration.

Last week Sanders declared that he had already won the policy debate. I think he was mainly right in this. On universal health coverage, Fight for $15, climate change policy, and much else, the party has moved significantly to the left in recent years, and much of the credit for this goes to Sanders.

Insofar as this is so, the policy differences between Sanders and Biden, while very real, are not that great, especially when one considers what must be done immediately to confront the coronavirus crisis. In any case, their difference pale in comparison to the contrast with Trump.

Sanders continues to be a visionary, an activist, and a mobilizer of a new generation of political leaders that promises to reinvigorate both the Democratic party and U.S. democracy itself. But he is almost certainly on the last leg of his final presidential campaign.

Biden continues to be Biden, the well-connected Democratic politician who has served at the highest levels of Congress and the White House. He lacks a grand or transformative vision. He promises executive experience, competence, and normalcy. And he has Ron Klain. Literally and figuratively.

This week, as a dangerous plague has dramatically befallen us, threatening the health, safety, and life of millions, the “normalcy” of Biden’s candidacy has come into even sharper relief. So too has the appeal of this “normalcy.” What in fact has happened is that Biden has come to the fore at exactly the moment when his modest virtues will be most evident.

It is likely that in the coming year the U.S., along with the entire world, will be dealing with the ongoing casualties and costs, and the long-term effects, of the coronavirus. What we need now is a President who can step right into the job of Chief Executive, who can quickly staff a new government with experienced people committed to public service who have real expertise, and who knows how to negotiate with world leaders and, yes, with even the awful Republicans who currently run the Senate and who will not go away even if we are lucky enough to have a Democratic Senate majority in January 2021.

The mobilization that Bernie Sanders, along with Elizabeth Warren, has led for years will and should continue. It will be carried forward by a new generation of leaders (see here and here). And it will hopefully help to shape the policies and personnel of a Biden administration. In these ways, Sanders has played an indispensable role in shaping the future of the Democratic party and the U.S.

Biden promises nothing but a respite from the traumatic stress disorder that is Trumpism and a Presidency that is serious, professional, and responsible.

Biden promises Ron Klain.

And right now — not a few weeks ago, and not a few years from now — Ron Klain in the White House is what we need.

Jeffrey C. Isaac is James H. Rudy Professor of Political Science at Indiana University, Bloomington.