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.