Joe Biden has created a war-cabinet-in-waiting on the coronavirus pandemic, with major figures from the Obama, Clinton and George H.W. Bush administrations drafting plans for distributing vaccines and personal protective gear, dramatically ramping up testing, reopening schools and addressing health-care disparities.

The effort began six months ago when the campaign consulted David Kessler, a former Food and Drug Administration commissioner under Presidents Bush and Bill Clinton, and Vivek H. Murthy, surgeon general under President Barack Obama, on how to run a presidential campaign during a pandemic.

The pair, along with a growing cadre of volunteer health experts, has been working behind the scenes to craft plans that could take effect Jan. 20, when the next president will take the oath of office, said Jake Sullivan, a senior policy adviser on the Biden campaign.

Biden has laid out a far more muscular federal approach than has President Trump, whose “failures of judgment” and “repeated rejection of science” the Democrat first pilloried in a Jan. 27 op-ed about the crisis. Biden has said that he would urge state and local leaders to implement mask mandates if they are still needed, create a panel on the model of President Franklin D. Roosevelt’s War Production Board to boost testing, and lay out detailed plans to distribute vaccines to 330 million people after they are greenlighted as safe and effective.

The Democratic presidential nominee’s “public pronouncements are not just about laying out an agenda for voters, but giving shape to an operational plan that he’s already starting to think about now for what Day One is going to look like,” Sullivan said.

Yet experts caution that even the best-laid plans will be challenged in a politically fractured nation where rampant disinformation about the novel coronavirusoften exacerbated by Trump himself — has complicated efforts to have people follow safety protocols like wearing masks and practicing social distancing.

“A lot of it is going to be out of Biden’s hands,” Angela Rasmussen, a virologist at the Center for Infection and Immunity at Columbia University’s Mailman School of Public Health, said of renewing faith in federal health officials. “It’s going to take time, and he is going to have to demonstrate that he’s restoring these agencies to their prior reputations through actions.”

By all accounts, the man who wins the Nov. 3 election will face a public health and economic crisis with little precedent. As of early September, the United States accounted for 4 percent of the world’s population but 23 percent of all coronavirus cases and 21 percent of deaths — a toll closing in on 200,000 and forecast to worsen significantly. Epidemiologists project a rise in cases and fatalities in late fall and winter as cold weather sends people indoors, students return to schools and colleges, and the pandemic converges with flu season.

Lindsay M. Chervinsky, the author of “The Cabinet: George Washington and the Creation of an American Institution,” said only a handful of incoming presidents have faced challenges as complex and dire as the one Biden would inherit if elected.

“With Biden, because this has been going on for a while, he would almost have to treat it as though he were starting from scratch and come up with a full-scale government response,” she said.

Biden has sought to make the crisis a referendum on Trump’s competence as well as his character.

At a campaign event Wednesday in Warren, Mich., he noted Trump’s assertions in recorded interviews with writer Bob Woodward that the president had intentionally played down the lethality and rapid spread of the coronavirus last winter, calling them “beyond despicable. . . . He knew how deadly it was. He knew and purposely played it down. Worse, he lied.”

Biden has also hammered Trump’s failure to take decisive steps to stem the spread of the virus. If the administration had acted early on, he said last week, “America’s schools would be open, and they’d be open safely. Instead, American families all across this country are paying the price.

The Democratic nominee would have the federal government take the lead on many aspects of the response, from scaling up testing and contact tracing to setting strong national standards, drawing a contrast with Trump, who has ceded many of those matters to the states, with the federal government serving as a “backup” and “supplier of last resort.”

Trump dismisses Biden’s criticisms, citing his decision to seal U.S. borders, suspending entry from China on Jan. 31. But with community transmission of the coronavirus already underway in the United States by then and difficulties in screening passengers, experts have said those restrictions were ineffective.

Amid an outcry about the unavailability of tests, Trump also appointed Vice President Pence to oversee a high-level task force to respond to the virus. But the president has often played down or contradicted the advice of health officials on that panel, whether on treatments such as hydroxychloroquine or on reopening the economy.

Above all else, he has insisted that the country’s economic crisis is as critical as its health woes and has urged Americans to return to school and work as the best way to salvage the faltering economy. (Most public health experts and economists argue that there cannot be a true economic recovery without first bringing the outbreak under control.) In recent months, Trump has also focused single-mindedly on the pursuit of a coronavirus vaccine, which he predicts will win approval by year’s end or sooner, as part of the expedited research, development and distribution of vaccines and treatments under Operation Warp Speed.

“Americans have seen President Trump out front and leading the nation in the fight against coronavirus . . . while Joe Biden has been behind the curve and fearmongering to discredit the president,” said Trump campaign spokeswoman Samantha Zager.

The Biden campaign said the virus’s toll speaks for itself.

“With nearly 200,000 dead, more than 6 million infected with the virus and nearly 30 million on unemployment, we desperately need action and new leadership now,” said Jamal Brown, the Biden campaign’s national press secretary.

As Biden and his aides piece together a national strategy, they are contemplating myriad questions: How many tests a day can the country conduct? Will states and health-care workers have needed protective equipment and supplies, or will they still be battling shortages and competing against one another? Might cases plateau at 40,000 a day or more, climb higher, or finally begin to taper off?

“There’s a huge amount of preparation that needs to be done given the complete absence of leadership from the current administration, and no time to waste,” Sullivan said.

Among the campaign’s top priorities are planning for the complex challenge of distributing one or more coronavirus vaccines to tens of millions of Americans; appointing a “supply commander” to coordinate the distribution of supplies to states and localities; and, perhaps most important, unifying the country and restoring public trust in the federal government’s message.

The last task may be the most difficult, aides acknowledge. To that end, immediately upon taking office, Biden would call Democratic and Republican governors and mayors across the country to ensure that not only does the federal government speak with one voice, but that Americans hear the same message from their state and local leaders, Sullivan said. He would urge state and local leaders to issue mandatory mask orders if necessary and to work together on a nationwide vaccination campaign.

Biden has also vowed to have public health experts and doctors hold regular news conferences on the pandemic.

With the situation rapidly evolving, Biden and his running mate, Sen. Kamala D. Harris (D-Calif.), continue to receive regular briefings on the state of the pandemic.

Beginning in March, Kessler and Murthy prepared briefing documents of 80-plus pages that set the agenda, Kessler said. Biden peppered them with questions, several campaign aides said. How do you keep essential services going? How do you keep people safe? What kind of equipment do we need to provide for front-line workers and their families?

The campaign put together a six-person advisory committee of health experts that, in addition to Kessler and Murthy, includes former Obama advisers Lisa Monaco and Ezekiel Emanuel; Rebecca Katz, director of the Center for Global Health Science and Security at Georgetown University Medical Center; and Irwin Redlener, a professor at Columbia’s Mailman School of Public Health.

The roster of experts offering advice, guidance and policy ideas has continued to grow rapidly, said several people familiar with the campaign.

Among Biden’s first appointments would be a supply commander, who would evaluate persistent shortages in equipment and test supplies, including swabs and reagents, his aides said.

That person would have to be able to identify bottlenecks and shortages in the supply chain for every component of tests, protective equipment and other material — whether the fabric used in N95 masks or reagents for diagnostic tests, said Nicole Lurie, a former Obama assistant secretary for preparedness and response and another campaign adviser.

Biden’s advisers have also prioritized planning for vaccine distribution on the assumption that one or more vaccines would be authorized, or close to such approval, by early next year.

“We’ve talked mostly about what’s going to be necessary to get a vaccine up and running, not just have a vaccine but actually produce it, bottle it, ship it out and vaccinate others,” said Emanuel, chairman of medical ethics and health policy at the University of Pennsylvania. “The logistics behind getting a vaccine to people is much more daunting than what people have thought through. . . . I don’t think our current infrastructure is sufficient.”

The Trump administration has a detailed vaccine distribution plan underway that the Centers for Disease Control and Prevention is overseeing, with backup from the Defense Department. At a news briefing last month, Trump said the United States is on pace to have more than 100 million doses of coronavirus vaccines ready before year’s end, and would partner with health-care giant McKesson to rapidly distribute them and related supplies as soon as one or more vaccines are approved. The administration has awarded billions of dollars to companies to manufacture those vaccines even before they win approval and to insulate them from the financial risks. It is also working with states and local governments on distribution plans that include supplies of syringes, plastic bandages and vials.

Unifying a bitterly divided nation might be the most difficult challenge of all, said aides and outside experts.

The single most important thing a President Biden must do would be to get buy-in for a new strategy from governors and mayors, as well as from the American people, said Leana Wen, an emergency physician and public health professor at George Washington University who was previously Baltimore’s health commissioner and is not part of the campaign.

Biden needs to be “the communicator in chief to turn this around,” Wen said. “He needs to convince people that they need to do what’s needed, while the government does what it needs to do.”

Otherwise, “if he orders a shutdown and 80 percent of people don’t comply, what good will that be?” she said, adding that it would be “a monumental task to get everyone on board.”

Biden’s advisers acknowledge that frequent and frank conversations with the American public will be essential.

“Lots of other countries have succeeded in controlling this, not because they have medicine we don’t, or a magic vaccine that we don’t,” Emanuel said. “They’ve been clear about the message, they’ve enforced it, and I think that’s what the future president is going to have to make clear to the American people — short-term pain for long-term gain.”