Former vice president Joe Biden has greenlighted a major hiring spree to shore up his campaign for the general election and calm roiling concerns among Democratic leaders about his operation’s scale and reach.

The additions, which involve dozens of staffers in all major departments, come as senior Democratic strategists and major donors have expressed concern for weeks about the massive advantages enjoyed by President Trump’s campaign. They’ve offered public and private warnings that though Biden leads in the polls now, his comparatively trim operation could prove politically fatal under an onslaught of Trump attacks this fall.

Some donors and strategists have argued that Biden needs to branch out from his basement studio — which has formed the backdrop for a campaign waged largely through uneven video streams, safe from the threat of the coronavirus — and leave the grounds of his Delaware home now that Trump has begun to once again travel the country.

Others have told the Biden team they fear that limiting the candidate to virtual appearances as Trump commands hours of airtime has left Biden on the sidelines while House Speaker Nancy Pelosi (D-Calif.) and state governors serve as the face of the Democratic pandemic response. Rather than highlighting Biden’s ideas to tackle the virus or revive the economy, much of the recent attention on him has focused on his denials of a former Senate staffer’s sexual assault allegations.

“The question is when does he come out — when is Groundhog Day?” said John Morgan, a Florida trial lawyer and major Biden donor. “That’s the big question. What is the first day of spring?”

Trump on Friday mocked Biden for his cloistered candidacy, offering to provide his rival’s campaign a rapid coronavirus test like the one used in the White House, while telling Fox News, “I’d love to see him get out of the basement so he can speak.”

Another top donor, speaking on the condition of anonymity to offer a candid assessment, suggested that Biden could think about ways to do events at police and fire stations or with nurses, keeping a safe social distance and wearing appropriate protective equipment.

Campaign officials, who declined to respond to Trump’s jibe Friday, have not yet signaled when Biden plans to leave his property.

Instead, the team is mapping a strategy that continues to emphasize virtual campaigning — effectively creating a contrast with Trump, who is eager to portray a sense that the country is returning to normal.

Biden’s advisers, who laid out their new expansion plans in interviews with The Washington Post, said the additional staffing and other changes will address many of the concerns they have been hearing.

The moves will include an initial doubling of Biden’s 20-person digital staff; new hires in fundraising and organizing; and the appointments of senior officials from the shuttered campaigns of former congressman Beto O’Rourke (D-Tex.), Sen. Elizabeth Warren (D-Mass.) and Sen. Kamala D. Harris (D-Calif.).

The long-expected expansion, coming more than eight weeks after Biden effectively sealed the nomination by winning the Michigan primary, was delayed in March by uncertainty about the campaign’s finances amid the pandemic, the logistics of building an organization without in-person meetings, and a strategic review by the campaign’s new leadership.

Biden’s campaign manager, Jen O’Malley Dillon, a field campaign specialist who took over the day before the campaign began working remotely, has overseen the planning for the new operation, previously bringing in a veteran campaign operative, Mary Beth Cahill, to become chief executive at the Democratic National Committee, and a veteran party fundraiser, Rufus Gifford, to serve as a third deputy campaign manager.

O’Malley Dillon said she has concluded that the campaign must build a robust operation for the summer and fall, heavily weighted toward fostering communities of Biden supporters online to challenge the enormous operation that the Trump campaign has organized over the past three years. Rather than continue the lean operation that Biden had through the primaries, she speaks of a grass-roots organizing model embraced by his rival Democratic primary candidates.

“Our operating theory here is we need to stay connected to people and organize, and create opportunities to engage with voters in ways that match this moment, when so many Americans are anxious and are eager for a sense of community,” O’Malley Dillon said in an interview.

The Biden campaign has begun to reposition the candidate in and around his home and has started to scale up its ability to reach out digitally, as nationwide social distancing enters its third month. After filming much of his content in a converted basement studio, Biden recently outfitted his house to give him the options of appearing live from a room with more natural light or from an outdoor spot on the property, according to digital director Rob Flaherty.

The moves may ease concerns among some Democrats that Biden has been losing crucial time to narrow the gap between his operation and the Trump campaign.

Two leaders of the last successful Democratic presidential campaigns, David Axelrod and David Plouffe, penned an opinion article in the New York Times this week with detailed instructions for how “Biden in the Basement” could improve his campaign. It was interpreted by some Democratic insiders as an unhelpful diminishing of the work going on behind the scenes to enhance the campaign.

“Online speeches from his basement won’t cut it,” the two strategists opined.

Since publishing their critique, both Plouffe and Axelrod, who said he was assigned the piece by a Times editor, have made clear that their suggestions were not meant as a criticism of O’Malley Dillon’s leadership.

“She could have written that piece herself,” Axelrod said. “She knows what to do and, from what I can see, is making progress.”

Much of what Democrats have called for publicly has been in the works, albeit at a small scale with mixed success so far.

The campaign has built a network of about 50 amateur content creators to craft online material to sell the Biden brand, including a recent interactive biographical tour of Biden’s life using mapping software. The volunteer effort is run by a middle school science teacher in Pennsylvania and a PhD candidate at Duke University.

Other campaign efforts online do not come with fingerprints. The campaign’s surrogate operation, run by the former figure skater Michelle Kwan, arranged Thursday for Mark Hamill, the actor who played Luke Skywalker in the Star Wars films, to respond to a tweet from Trump campaign manager Brad Parscale that compared the Trump effort to the Death Star.

“Once you start down the dark path, forever will it dominate your destiny,” Hamill tweeted, a quote from Yoda in the movie series, which he paired with the hashtag #Red5StandingBy, a line his character speaks before destroying the galactic superweapon in the original 1977 film.

While the Trump campaign online has embraced a macho and combative approach — “This ­account punches back 10x harder,” runs the motto of one campaign Twitter account — the Biden team has been seeking to develop a more uplifting identity online, embracing the candidate’s life story and making light of his love of ice cream and aviator sunglasses.

“Trump’s angles on social media are always dark, and they are always mean-spirited,” said Ben Cobley, a Biden digital organizer. He said Biden wanted to build a community around the more positive side of social media, populated by inspiring memes and cat videos. “We want to lean into that side of the Internet because that side also plays very well.”

The campaign has so far focused much of its digital efforts on building community inside existing social networks, an effort that the campaign has dubbed the Soul Squad, a reference to Biden’s promise to restore the country’s soul.

“Usually we were trying to get people to physically come to our events, trying to get people to take photos,” said Eisha Misra, another digital organizer. “This is a totally different way of seeing people online.”

The campaign, which outspent Trump online in March, said it has gotten more than 100 million video views since mid-March, has more than doubled the size of its email list and recently held a training for about 700 digital volunteers.

The online organizing effort is based around thematic goals like “compassion,” “faith,” “resilience,” “kindness” and “humility.”

“When Trump fights, we’re going to fight harder. But our north star is showing empathy and connection,” said Flaherty, the digital director. “The way you win is not by being conflict-driven.”

The campaign has also begun to redesign its graphics and branding, a project undertaken by Robyn Kanner, who has joined Biden as senior creative adviser after working for Beto for America, New Balance, Google and Amazon.

Caitlin Mitchell, the chief mobilization officer for Warren for President and the Democratic National Committee, has also joined the Biden campaign to advise on digital strategy and help quickly scale up in-house teams for fundraising and voter outreach.

Andrew Gauthier, a former head of BuzzFeed Video who ran digital content for the Harris campaign, has joined the Biden effort as its video director.

Since the primary race, the campaign has had just two video producers, limiting its ability to combat the rapid online responses that have become rote for the Trump operation.

The Biden campaign’s challenge was on display Thursday as an attempt to stage a virtual tour and rally in Florida, with the candidate addressing the nation from an upstairs room in his home, was marred by technical failures.

But there were signs of hope for Biden’s team Friday, when he delivered a 13-minute economic speech streamed live on NowThis News. He stood in the same spot where he spoke the night before, against the backdrop of a large window offering a view of trees and flowers. This time, there were no technical difficulties.

CORRECTION: An earlier version of this story incorrectly stated the location of a middle school science teacher leading the volunteer content creation effort.