"This administration has left us woefully unprepared for the exact crisis we now face," Biden said in a speech delivered from his hometown of Wilmington, Delaware, and tailored to draw sharp contrasts between the former vice president and the Republican incumbent he hopes to topple this fall.
A short time later, Biden's last Democratic presidential rival, Vermont Sen. Bernie Sanders, said the outbreak may isolate Americans working from home and in quarantine and he suggested the country needed to band together, not divide.
"If there ever was a time in the modern history of our country when we were all in this together this is the moment," Sanders said. He said of Trump's White House, "We have an administration that is largely incompetent and whose incompetence and recklessness have threatened the lives of many, many people in our country."
Biden said he is already up to meeting such challenges better than Trump.
"No president can promise to prevent future outbreaks, but I can promise you this, when I'm president we will be better prepared, respond better and recover better," Biden declared. "We will lead with science, listen to the experts, will heed their advice. We'll build American leadership and rebuild it to rally the world to meet the global threats that we are likely to face again."
Biden cautioned that the virus, which some Trump allies have dismissed as overblown fodder for the president's critics, "does not have a political affiliation." And in a direct dig at Trump, Biden added another pledge: "I'll always tell you the truth. This is the responsibility of a president. That's what is owed the American people."
The former vice president and Sanders gave their dueling addresses on the coronavirus less than 24 hours after Trump spoke to the nation from the Oval Office about a public health crisis he'd previously downplayed.
Sanders called on Trump to declare a national emergency and said a hotline should be established for people seeking information about coronavirus.
He also said the U.S. was at a "major disadvantage" compared with other countries since many people have no medical insurance.
Sanders has advocated for fully government-financed health care under a "Medicare for All" system that is the centerpiece of his campaign. But he said Thursday that in the meantime during the outbreak, the government must ensure that, "Everyone must be able to get all of the health care that they need without cost." He added that if a vaccine to the virus is developed, it should be free.
"We need an emergency response to the current emergency," Sanders said, "and we need it immediately." With his speech, Biden unveiled a slate of policy proposals and said Trump is "welcome to adopt all of it today." Biden called for all medically necessary testing for the virus to be accessible and without cost. He called for Congress to enact paid leave for all Americans, both as a temporary fix in responding to the current health crisis and a long-term solution to what he describes as a key gap in U.S. labor practices. Biden also proposed mobilizing federal resources to ensure at least 10 testing sites in every state and providing federal aid, including from the Pentagon, to put a stand-up hospital in any American city where an outbreak exceeds the capacity of existing health care infrastructure. Biden pledged that his administration would hold daily briefings in any such crisis, with top public health professionals in front of cameras to address the nation directly.
Hours later, Biden campaign leaders said in a memo that beginning Saturday, all campaign staff -- at Philadelphia headquarters and in field offices around the country -- will work from home. All Biden offices will be closed to the public.
The campaign also said all fundraisers will become virtual events indefinitely, with pooled press access. Biden has virtual campaign events scheduled for Friday in Illinois and Monday in Florida, replacing planned rallies.
The memo, signed by senior strategist Anita Dunn and new campaign manager Jen O'Malley Dillon, states that "small gatherings are safe," according to public health officials, provided no exposed persons participate. "We will continue to hold smaller events like roundtables, house parties, and press statements, as well as virtual events, like tomorrow's virtual town hall," the pair wrote.
Similarly, Sanders spokesman Mike Casca announced that "out of an abundance of caution for our staff, volunteers and supporters" the campaign has asked all staff to work from home and "will no longer hold large events or door-to-door canvasses, instead moving to digital formats and outreach wherever possible."
Aides said the aim of Biden's speech, besides addressing the current situation, was to give voters a practical example of one of his core arguments: that he'd be ready on Inauguration Day to handle whatever trials reach the Oval Office. In some ways, the dynamics recall the financial crisis that mushroomed late in the summer of 2008. The meltdown further damaged outgoing President George W. Bush and his Republican Party, dealing GOP nominee John McCain a new setback and granting a wider opening for Democratic nominee Barack Obama and his running mate, Biden. But that unfolded weeks before the election - Biden must keep making his case for nearly eight months.
Biden now leads Sanders by more than 150 delegates after winning four more state primaries Tuesday, with Washington state still being counted. And his advantage could expand considerably next Tuesday when the delegate-rich states of Florida, Illinois and Ohio hold primaries.
Biden and Sanders will meet in a debate Sunday night on CNN, without a live audience.
For most people, the new coronavirus causes only mild or moderate symptoms, such as fever and cough. For some, especially older adults and people with existing health problems, it can cause more severe illness, including pneumonia.
Sanders is 78. Biden is 77.
The vast majority of people recover from the new virus. According to the World Health Organization, people with mild illness recover in about two weeks, while those with more severe illness may take three to six weeks to recover.
Regardless of how Biden handles the moment, the coronavirus outbreak comes at a political juncture for him.
He's solidified his position as the prohibitive favorite for his party's nomination, but Sanders has made clear he's not ready to abandon his campaign, and many of the senator's supporters on the progressive left aren't enthusiastic about embracing Biden as the Democratic standard-bearer. That slice of the Democratic coalition likely isn't enough to derail Biden's nomination, but it could complicate his efforts in a general election campaign, just as it did for Hillary Clinton in 2016 after she defeated Sanders but lost to Trump in November.
Projecting leadership on a grave public health matter could be a boon with the middle of the electorate, especially independents and moderate Republicans wary of Trump. But it won't necessarily corral Sanders supporters who also will play key roles in deciding battleground-state outcomes in November.
For his part, Trump said Thursday he's "very happy to run against" Biden.
"One of the reasons I ran for president was because of Joe and the job they did," Trump said, referring to Biden's time as Obama's vice president. "It's maybe the way it should be."