Sen. Bernie Sanders is facing massive division in his own campaign, lagging momentum and uncertainty on whether he will secure fellow progressive Elizabeth Warren’s endorsement — with just days until the must-win Michigan primary.

Warren, who could help Sanders unite the progressive wing of the party with an endorsement, has decided that she wants to “take a deep breath and spend a little time on that,” instead of rushing into his corner.

Warren’s supporters seem to want to spend a little time on that as well.

Recent polling by the New York Times found that Biden appears likely to pick up just as many Warren supporters as does Sanders, something that could cripple the Vermont senator’s chances at clinching the nomination.

“Obviously the more strong liberal policy folks should break more for Sanders than Biden, but I don’t know that it’s going to be anywhere near unanimous,” longtime Democratic pollster Paul Maslin told the paper.

“If Biden is over the hump and is now clearly the accepted candidate as the best to beat Trump, and there’s a coalescing of the party around that view, he’s going to gain all kinds of support,” he added.

Warren’s base is heavily made up of college-educated white women, a group that Sanders has consistently struggled to reach.

“For most suburban or upper-middle-class white women, Joe Biden is a pretty comfortable place to land,” Maslin said, “There’s the Obama connection, there’s a sense of stability and experience that’s probably pretty helpful, and then to the extent that they’re being pragmatic, they probably see him as a potentially stronger candidate against Trump.”

Warren’s lack of praise for Sanders since dropping out only hurts the presidential hopeful’s chances with the group.

On Thursday night, Warren trashed Sanders’ supporters and their candidate’s unwillingness to stop their cyber-harassment.

Speaking to MSNBC host Rachel Maddow, Warren claimed that so-called Bernie Bros, as Sanders’ staunchest supporters have come to be known, posted the home addresses and phone numbers of numerous women of color who worked for or ran groups that had either endorsed her or not endorsed Sanders.

The move, she said, led to an “onslaught of online threats.”

“Working Families Party, two women there, women of color…were attacked right after they endorsed me,” the Massachusetts progressive said.

“I wanna say this for all of the candidates, back when there were lots of us, we are responsible for the people who claim to be our supporters and do really threatening, ugly, dangerous things,” she remarked.

When asked by Maddow if this was a particular problem with the Democratic socialist’s supporters, Warren answered with an adamant yes.

“It is, it just is.”

Meanwhile, inside Sanders’ campaign, a divide has emerged over the best strategy to combat his current shortcomings, according to the Associated Press.

Sanders campaign manager Faiz Shakir has argued that they should double down on their existing pool of supporters, while Jeff Weaver, Sanders’ closest aide, believes pushing for more endorsements and broadening the coalition is necessary to secure the nomination.

Despite Shakir’s push for a focus on existing campaign surrogates such as Reps. Alexandria Ocasio-Cortez, Ilhan Omar and Rashida Tlaib, campaign aides have expressed frustration at their candidate’s unwillingness to do the necessary work to earn more endorsements.

Their frustration is worsened as they watch Biden rapidly expand his number of endorsements.

Biden has now gotten the support of a large number of former 2020 Democrats, including former Mayors Pete Buttigieg and Mike Bloomberg, former Rep. Beto O’Rourke and Sen. Amy Klobuchar. The former vice president was also reported to have been courting Sen. Kamala Harris for her support, The Times reported last month.

As for now, which side Warren will join remains unknown.

A spokesperson for Sanders’ campaign did not respond to repeated requests for comment from The Post.

With Post wires