Senator Bernie Sanders began his live-stream presentation about the coronavirus on Saturday night as he begins nearly all of his events: by thanking the musicians who performed before he took the microphone.
“I want to thank Soccer Mommy for their great music,” he said, staring into the camera from his home in Burlington, Vt.
The next day, a senior adviser for his campaign tweeted that clip of Mr. Sanders with her own words of gratitude — and an impassioned plea: “I want to thank Bernie for staying in the race,” she wrote, adding the hashtag #StayInBernie.
Mr. Sanders is still in the Democratic presidential race for now, trailing badly in the delegate contest with just one primary looming on the distorted political calender: Wisconsin votes on Tuesday.
Just weeks ago, aides and supporters of Mr. Sanders had optimistically pointed to the Wisconsin primary as a possible springboard for revitalizing his campaign, viewing him as well positioned to recapture a state that he dominated in his 2016 presidential bid — even as he continued to lose race after race to his rival, former Vice President Joseph R. Biden Jr.
It may instead be his last stand. A recent poll showed him far behind Mr. Biden in the state, and top Sanders advisers have all but ceased speaking about his chances there. Results are not expected to be known until possibly next week, but if Mr. Sanders suffers another big loss, it is certain to intensify the growing calls for him to exit the race.
In the weeks since the coronavirus crisis put the campaign on hold, Mr. Sanders has tried to convert his political operation into a virus-focused initiative. The effort has kept his supporters engaged, applied political pressure to protect workers and raised millions of dollars for charities to help people dealing with the outbreak. But it has done little to shift the dynamics of his contest with Mr. Biden.
As the coronavirus has continued to wreak havoc on the Democratic election, pushing off nominating contests to June and eroding candidates’ abilities to run traditional campaigns, the Wisconsin primary now looms as a potential pivot point for the Sanders campaign.
In public, Mr. Sanders, a Vermont liberal, has insisted he still has a “narrow path” to the Democratic nomination even as he has acknowledged his delegate deficit. But since the last round of primaries on March 17, he has been assessing his campaign and seeking the opinions of supporters, including his campaign co-chairs and members of Congress who have endorsed him.
Top advisers and key allies have been offering different viewpoints about whether Mr. Sanders should stay in or drop out — and he has been weighing all of them, according to one top aide, who spoke on the condition of anonymity to discuss private conversations. And among those close to him, there is a split about what he should do.
Some of Mr. Sanders’s closest advisers have mapped out the financial and political considerations for him and what scenarios would give him the maximum amount of leverage for his policy proposals, and some have concluded that it may be more beneficial for him to suspend his campaign.
“I told Senator Sanders I would support whatever he decides,” said Representative Ro Khanna of California, one of Mr. Sanders’s national campaign co-chairs. “He is weighing wanting to support the nominee 110 percent and defeat Trump with his obligation to millions of his supporters who want to vote for his vision for America. It’s a difficult decision, and I respect whatever he decides.”
Some of his top advisers have held back-channel discussions with the Biden campaign on matters including preparedness for the coronavirus and the outbreak’s impact on the economy. Mr. Biden has also said repeatedly that he has spoken with Mr. Sanders about his process for selecting a running mate. In an interview with ABC’s “This Week” on Sunday, Mr. Biden said that he had apologized to Mr. Sanders for having already set up a selection committee and that he had not wanted to appear presumptuous.
“I was apologizing to him by saying, Bernie, I don’t want to in any way and not in any way to demean your effort, but if we don’t start now, we’re not going to be able to get there,” Mr. Biden said. “And he was very gracious. He said he understood.”
There is also a large and vocal cohort of supporters who are encouraging Mr. Sanders to forge ahead.
Larry Cohen, a longtime Sanders ally and the chairman of the Sanders-aligned political organization Our Revolution, has urged him to continue running. In an op-ed last week, Mr. Cohen argued that staying in the race would give Mr. Sanders’s allies the opportunity to win seats on the powerful rules and platform committees at the Democratic convention; without that leverage, the party could revert to rules that progressives fought hard to change in 2016, including resurrecting the power of superdelegates.
“If Bernie stays in, then even if Biden is the nominee, we have a much better chance to fight for a more progressive Democratic platform and preserve vital reforms in the party’s nominating process,” Mr. Cohen wrote in an email to Our Revolution supporters on Monday.
But in a sign that the group’s resolve may be softening, the email also contained a survey that asked supporters to indicate whether they believed Mr. Sanders should stay in or if it was “time to unite behind Joe Biden.”
For now, Mr. Sanders is pushing on. His campaign has more than 50 staff members dedicated to Wisconsin. It has made more than 300,000 calls to voters and continues to use its proprietary Bern app to connect with supporters. On Friday, it held a “virtual barnstorm” featuring Representative Mark Pocan of Wisconsin and Randy Bryce, a surrogate, who have both endorsed Mr. Sanders. It is still conducting get-out-the-vote efforts — not for in-person voting but on absentee balloting — and it is keeping Wisconsin Democrats updated on the state’s process.
As he fights to stay in the race, Wisconsin is as important electorally to Mr. Sanders as it is symbolically. In 2016, he trounced Mrs. Clinton in the state, winning 71 of 72 counties, a triumph that galvanized his campaign.
But his support, which even several weeks ago looked robust, has softened significantly, in part because he is no longer running against Mrs. Clinton, who was particularly polarizing in the Midwest. Many of the same voters who once backed him have coalesced behind Mr. Biden for the same reason that so many other voters have: They believe Mr. Biden is more likely to defeat President Trump. The uncertainty surrounding the coronavirus has seemed to only accelerate that choice.
“People are so scared of a Trump re-election that they are voting for who they think has the best chance of winning,” said Kim Butler, the Democratic chairwoman in Polk County, Wis. “For many, that is Biden.”
Reid J. Epstein contributed reporting.