With President Trump providing daily televised briefings and governors like Andrew M. Cuomo emerging as national leaders during the coronavirus pandemic, former Vice President Joseph R. Biden Jr. is still grappling with how to position himself as a prominent voice on a crisis that is pushing traditional politics to the background.

Mr. Biden has been confined over the last week to an unusually small role for the likely — though not yet completely certain — nominee of a major political party. His public comments have been sparing and, for the most part, restrained. He is now ramping up a public schedule, beginning with an appearance on ABC’s “The View” on Tuesday, and his aides said he would offer remarks on camera in some fashion each day.

But Democratic strategists, some state officials and even some of his own aides have said that Mr. Biden needs to be more visible at a time when Americans are looking for leadership. The challenge for Mr. Biden, they say, is to find ways to draw sharp contrasts in leadership style with Mr. Trump while showing sensitivity to the severity of the crisis, and to break through when the nation is focused on more immediate concerns than November’s election.

Jim Margolis, a veteran Democratic strategist, said Mr. Biden had “walked that line really well, but it’s hard.”

“The task is, are you able to cut through?” Mr. Margolis said. “Are you able to cut through when Americans are consumed by a virus that is in the news, and that’s all that’s being discussed, whether on the Senate floor, the White House briefing room or in emergency rooms?”

Some Democrats have been perplexed at why Mr. Biden has not used his newfound free time to blitz television news shows, many of which are enjoying high ratings with so many people confined to their homes. He did not do any of the Sunday morning news programs and has also been absent from daytime cable news, which has been dominated by the daily briefings of Mr. Trump and Mr. Cuomo.

On Monday, a day after one of his own donors asked how he could become a bigger part of the national conversation, Mr. Biden gave a speech that was streamed live from his home in Delaware in which he criticized Mr. Trump’s response to the virus as too slow and insufficient, and pressed him to act like the “wartime president” he says he is.

But his address offered a reminder of the continuing challenge he faces in getting attention, even when he does speak out. CNN, Fox News and MSNBC did not air his speech, instead showing a briefing by Mr. Cuomo of New York.

“The whole country is focused on one issue and one issue only,” said Teddy Goff, who served as a top digital strategist for the campaigns of President Barack Obama in 2012 and Hillary Clinton in 2016. “It’s certainly going to be very difficult to break through on other issues. But it’s essential for the person who’s highly likely to be our Democratic nominee to have a strong voice on this issue.”

Andrew Bates, a spokesman for the Biden campaign, said, “These are uncharted waters for any campaign but our campaign is ready to carry Joe Biden’s message forward through innovative virtual events and digital outreach.”

“Vice President Biden’s voice represents competence, strength and empathy,” he added, qualities he said the nation was craving “as we confront unprecedented challenges.”

Mr. Biden has reached out to the House speaker, Nancy Pelosi; the Senate minority leader, Chuck Schumer; Mr. Cuomo; and Gov. Jay Inslee of Washington, among others, to express his concern and solicit their thoughts about how to confront the pandemic, according to Democrats familiar with the conversations.

Credit…Al Drago for The New York Times

But advisers to Mr. Biden have acknowledged the need for a more robust public presence than the former vice president has managed since his victories in last Tuesday’s primaries, describing the process of finding the right tone and format for Mr. Biden’s message as a work in progress. His campaign has assured political donors and other supporters that it is testing different approaches and formulating a strategy for using TV and digital options for projecting his personality and delivering criticism of Mr. Trump.

Mr. Biden intends to significantly increase his public activity this week, according to an aide familiar with his plans: In addition to appearing on “The View,” he plans to call into radio shows and take questions from reporters, and he is likely to hold a virtual town hall and some kind of question-and-answer session on social media. Additional television appearances are in the works.

Mr. Biden’s direct rebuke of the president on Monday morning was by far his sharpest set of comments on camera since the virus began to spread in the United States. “Let me be clear: Donald Trump is not to blame for the coronavirus, but he does bear responsibility for our response,” he said. “And I, along with every American, hope he steps up and starts to get this right.”

Mr. Biden’s reluctance to take a more prominent role as the crisis deepened reflects in part his personal instincts and sense of political boundaries, according to his advisers and close allies. A more than 40-year veteran of the legislative and executive branches, he is deferential to his party’s current leaders and does not want to complicate their already difficult tasks at a moment of crisis.

That kind of calculation has surfaced before in this campaign. Last year, for example, he was reluctant to push for Mr. Trump’s impeachment in part because he did not want to put pressure on Ms. Pelosi and members of her caucus. This left him in the odd position of being the last of the major Democratic candidates to call for impeachment, even though the charges involved Mr. Trump pressing for an investigation into Mr. Biden and his son.

Mr. Biden still has the unresolved matter of the Democratic primary, though the party’s major institutions have continued to swing behind his candidacy even amid the quasi-national lockdown. The American Federation of State, County and Municipal Employees endorsed Mr. Biden on Monday, and another major union, the American Federation of Teachers, backed him on Sunday.

Complicating matters for Mr. Biden is the reality that, for the first time in decades, he is campaigning for office without an existing role in government, of the kind he had as a senator when he ran for vice president during the 2008 economic meltdown. Mr. Biden released a plan to address the coronavirus this month, but unlike many of the senators and governors who competed against him for this year’s Democratic nomination, he has no active position from which to shape policy.

For much of the 2020 campaign, that detachment from daily governing was an asset to Mr. Biden, freeing him from the confines of a day job managing a state or casting votes on legislation. Now, however, it has left him further from the center of action than former rivals like Senators Elizabeth Warren of Massachusetts and Kamala Harris of California, or his lone remaining competitor, Senator Bernie Sanders of Vermont.

Mr. Biden’s answer so far has been, in part, to build a kind of government-in-exile, showcasing the policy experts he would draw upon in the White House and seeking to present a contrast with Mr. Trump’s approach. A public health advisory committee Mr. Biden named this month was something of a model: His advisers are said to be assembling a far larger network of policy experts than the one he employed throughout the Democratic primary.

Those experts may begin to take a larger role as surrogates for the campaign on television and online. The Biden campaign was encouraged by the response it got over the weekend to a four-minute video it posted featuring Ron Klain, a former chief of staff to Mr. Biden who coordinated the Obama administration’s response to Ebola. The straightforward, policy-heavy presentation, which unpacked the current pandemic and pinned heavy responsibility on Mr. Trump for his response, got more than four million views on Twitter.

But Mr. Biden’s absence from public view made him the subject of taunts on Twitter, where hashtags like #WhereIsJoe have been used to skewer him, including by Trump campaign officials. “Is Ron Klain now the Democrat candidate for president?” Tim Murtaugh, the Trump campaign’s communications director, wrote on Twitter on Saturday.

And during a virtual fund-raiser on Sunday, Mr. Biden fielded a question about his limited visibility. “What I’m concerned about is that we see Donald Trump every day with this crisis giving his press report,” a donor said, according to a pool report. “And I would just love to see you more. Like, how do we get more of you and less of him on our airwaves?”

To help Mr. Biden reach the public even while he is hunkered down, his campaign turned a room in his house into a makeshift television studio. He spoke on Monday from a lectern bearing a Biden sign, just as if he were on the campaign trail.

The nation’s “focus, for at least the short term, is not going to be on the presidential race,” said Mr. Margolis, the veteran Democratic strategist. Still, he continued: “Four weeks from now, you have to make sure you’re engaging in a campaign that is going to be decided this year. He does not have the opportunity to sort of sit back and wait three months to see where the whole thing lands.”

Jonathan Martin and Katie Glueck contributed reporting.