In a direct rebuttal to President Donald Trump, Joe Biden and Bernie Sanders delivered somber, and at times searing, speeches Thursday slamming the administration's handling of the coronavirus pandemic and detailing how they believe the government should be responding to the crisis.

"If there ever was a time in the modern history of our country where we are all in this together, this is that moment," Sanders said in Burlington, Vermont, after suggesting the death toll may exceed that of American service members during World War II. "Now is the time for solidarity."

Earlier, in an address from his hometown, Wilmington, Delaware, Biden said, "Downplaying it, being overly dismissive or spreading misinformation is only going to hurt us and further advantage the spread of the disease."

"But neither should we panic, or fall back on xenophobia," he said. "Labeling COVID-19 a foreign virus does not displace accountability for the misjudgments that have been taken thus far by the Trump administration."

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The two candidates spoke the day after Trump addressed the nation as his administration seeks to quickly mitigate the virus' impact on public health and financial markets.

Biden's speech was the first he's made since he emerged as the front-runner for the Democratic presidential nomination in a campaign in which he has overtly suggested to the American public that he's better prepared than Trump to handle a crisis as commander in chief.

And he did not shy away from offering policy prescriptions — and taking on Trump.

"Let me be crystal clear. The coronavirus does not have a political affiliation. It will infect Republicans, independents and Democrats alike. And it will not discriminate based on national origin, race, gender or ZIP code," he said.

Biden added that "this virus laid bare the severe shortcomings of the current administration."

"Public fears are being compounded by a pervasive lack of trust in this president fueled by adversarial relationships with the truth that he continues to have," he said.

Biden's plan to combat coronavirus would include free testing for the virus and the elimination of all cost barriers to preventive care and treatment for the disease the virus causes, his campaign said in a statement released while he was speaking.

And amid the rapid spread of the virus — a pandemic that has caused the stock market to plummet and sporting leagues to suspend their seasons — Biden used his speech Thursday to assert his qualifications to be president.

Sanders, meanwhile, said there is an "absolute moral imperative that our response as a government, as a society, as a business community and as individual citizens meet the enormity of this crisis."

The senator from Vermont railed against the Trump administration's "incompetence and recklessness," which he said has "threatened the lives of many people in our country."

He called on Trump to declare a national emergency and convene a bipartisan authority of experts to lead the response, which should be based "first and foremost on science and fact."

Now, Sanders said, is the "time for transparency and honesty and being straightforward."

Reiterating his support for "Medicare for All," Sanders said everyone in the country "must be able to get all of the health care they need without cost," that emergency funding must be passed for paid sick leave and that the U.S. must make sure it is using the latest and most effective testing possible, among other prescriptions, such as a moratorium on evictions.

"We need to make sure that in the future ... we build a health care system that makes sure every person in this country is guaranteed the health care they need," Sanders said.

Both candidates have, in recent days, taken Trump to task over his handling of the crisis. Biden's message has zeroed in on the administration's response, highlighting his experience in the Obama administration, while Sanders has argued that his progressive agenda, including programs like Medicare for All, is more necessary than ever in light of the health scare.

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Rebecca Katz, a progressive strategist, pointed to exit polling in recent Democratic primaries showing majority support for Medicare for All, telling NBC News the crisis "is now a way to explain to everybody else who may have doubts why it's so important that we need to do more, we need to do better for our people."

Universal health care and paid sick leave "are very important" in the context of this moment, she added.

Biden and Sanders have canceled in-person campaign events in light of the crisis, and Biden has announced the formation of a public health advisory committee to assist his campaign with responding to the rapidly spreading coronavirus.

Political communication experts told NBC News those moves suggest Biden is attempting to seize on the disorder created by the pandemic.

"In this case, this is not just about communication. It's also about public health. And your responsibility as a political leader is not only to send the message to the public, it's to serve as an example to the public," said Jennifer Glover Konfrst, a professor of strategic political communication at Drake University,in Des Moines, Iowa.

Trump, in contrast, has come under increasing fire in recent weeks over his response to the pandemic while his administration has come under enormous criticism for the lack of coronavirus testing being done compared with other countries, something both candidate's pointed to in their addresses Thursday.

In addition to having insisted for weeks that he had the outbreak under control, Trump also propagated personal beliefs about the coronavirus that contradict those of veteran health officials and experts.

Health officials in recent days have sounded the alarm, warning the public that the outbreak is likely to get worse. Many major public events, including all NBA, NHL, MLS and MLB preseason games and Broadway shows, have been canceled this week, and Thursday saw the Dow's worst day since the 1987 crash.

As panic began to set in, Trump tried to quell the fears of Americans across the country by giving a speech from the Oval Office on Wednesday night. He announced that he would ban many foreign travelers from Europe for the next 30 days and offered a series of economic relief actions to help workers and companies deal with the outbreak. But his speech was met with swift pushback after he misstated several aspects of the policy and failed to propose any new action to combat the outbreak domestically.

Meanwhile, voters have seemed to express a growing sense of trust in Biden's ability to handle a crisis — even before Biden made his latest moves.

An NBC News exit poll on Super Tuesday found that Biden was the candidate of choice of nearly half of those who rated the outbreak as an important factor, above Sanders. And a Quinnipiac University Poll released Monday showed that 49 percent of registered voters across the U.S. said they disapproved of Trump's response to the coronavirus. Forty-three percent said they approved.

Philippe Reines, a former senior adviser to 2016 Democratic presidential nominee Hillary Clinton, told NBC News that Biden's experience in the previous administration gives him "a real leg up" on the issue.