Former President Barack Obama’s top lieutenants are eager to poke every conceivable hole in Bernie Sanders’ resurgent bid for the Democratic nomination. But ask about a coordinated effort to stop his ascending campaign and you’ll get crickets.

Less than a month before voting begins, Obama has declined to offer a preferred pick to take on President Trump in 2020, only occasionally waxing philosophical about the perils of moving too far left and reminding voters to be “rooted in reality” when exploring nominee options. But as Sanders gained new flashes of traction in recent weeks, the former president’s lack of official guidance to halt his momentum, and the scattering of his inner circle to rival campaigns, have hampered any meaningful NeverBernie movement.

Indeed, the most striking aspect of Obamaworld’s response to Sanders on the rise—flush with cash, an uptick in the polls, and unusually frequent hat tips about the merits of his character from his rivals—is the lack of a cohesive one.

Seasoned Obama operatives who spoke to The Daily Beast concede that Sanders is likely to be a major player through the end of the primary, with several agreeing there’s little to no consolidation around one anointed candidate to blunt his momentum. In fact, while pointing to his massive cash hauls and loyal base of supporters, the thinking among Democrats close to the former president is that they are hoping the Vermont Independent flames out on his own.

“Money is important but doesn’t always translate to votes,” Neera Tanden, who served as policy director for the Obama-Biden presidential campaign, told The Daily Beast.

Sanders recently posted his biggest fundraising haul to date, having raised an eye-popping $34.5 million, far surpassing his closest rivals, with South Bend Mayor Pete Buttigieg coming up approximately $10 million short of that sum at $24.7 million. Shooting down criticism that he hasn’t expanded his base from 2016, his campaign points to a newly released number, boasting that 300,000 new donors gave to his campaign last quarter, a sign of increased grassroots strength and enthusiasm from previous showings. And in a departure from his competitors, including Biden, his campaign has regularly pledged not to do big-dollar fundraisers in the general election.

“He’s never going to run out of money,” one former top Obama adviser acknowledged when asked by The Daily Beast about the chances Sanders could secure the nomination. But it’s not enough of a concern to plan a big strategy around, the source said. “He’s going to be a zombie candidate. You can go anywhere and still be dead.”

Multiple allies believe the self-avowed democratic socialist posed a bigger threat in 2016, when he mounted a challenge to Hillary Clinton and ultimately captured over 40 percent of the primary vote. This time, those sources believe, he has greater problems complicating his path to the nomination: namely the presence of more top-tier contenders in the field, including a progressive in his own lane in Sen. Elizabeth Warren (D-MA). On top of that, while he’s consistently polling nationally in second place, he hasn’t achieved the same degree of overwhelming support among African-American voters as former Vice President Joe Biden, who has dominated with that key Democratic constituency. Others simply believe his past legislative history with the 44th president is too complex to cast as rosy.

“If you read between the lines of what the Sanders folks are saying about the rationale of his candidacy, it is based on their belief that Barack Obama was not progressive,” one former senior Obama campaign staffer told The Daily Beast. “There is a fundamental flaw in the Sanders candidacy relative to the Obama coalition and it’s because they’ve continually undermined President Obama.”

Privately, Obama has reportedly acknowledged problems with Sanders’ vision for the country. In November, Politico reported that the former president once said that if it looked like the senator were close to winning the nomination, he would speak up in some capacity to help stop that from happening. A spokesperson later muddied the waters when asked about the comment by the outlet, saying that Obama would support the nominee. Still, Obama’s rare public statements give a glimpse into his thinking about Sanders 2020.

Speaking to Washington donors in in November, Obama cautioned against placing too much stock into “certain left-leaning Twitter feeds or the activist wing of our party.”

“Even as we push the envelope and we are bold in our vision we also have to be rooted in reality,” he said. “The average American doesn’t think we have to completely tear down the system and remake it.”

Sanders, who built both of his presidential campaigns around the notion of a “political revolution,” is explicit in his intent to restructure major swaths of America’s governing systems. His most fervent legislative push, a universal health-care pitch in the form of Medicare for All, has dominated much of the Democratic primary discourse. And while Sanders’ campaign, which did not respond to a request for comment on this story, views his progressive health-care position as one of the strengths of his candidacy, others see it as one of the biggest points of contention, evoking tense flashbacks.

Heading into the 2012 re-election campaign, one top Obama ally recalled how “the most vocal opposition came from not just Sen. Sanders but the folks that are currently leading his campaign” over health care. “I don’t think anyone has forgotten that,” the source said.

Still, with just 28 days before voting begins in earnest, Sanders has shown more sustained momentum—boosted by a coveted endorsement from Rep. Alexandria Ocasio-Cortez (D-NY), strong showings in several early-state surveys, and hundreds of thousands of new donors. And, as The Daily Beast reported, his competitors have so far failed to lay a glove on him in a meaningful way during the first several Democratic debates. He is one of only five contenders to qualify for the upcoming debate in Des Moines.

The fact that Sanders has enough money and apparent support to compete well beyond the first few early contests and through Super Tuesday, the marquee, delegate-rich event in March, has caused other former Obama hands to take note.

“Bernie Sanders' chances of winning the nomination are being underestimated and under-discussed. He might be the candidate with the best chance to sweep IA, NH, NV before we ever get to South Carolina,” Dan Pfeiffer, one of Obama’s former senior advisers, wrote last month, linking to a Monmouth University national poll that placed Sanders at 21 percent, behind Biden’s 26.

Now, that gap in several early states is even narrower. A pair of new CBS News/YouGov polls released on Sunday show Sanders leading the pack in New Hampshire, earning 27 percent, with nearly half of his voters in the Granite State saying they have definitely made up their minds. In Iowa, the Vermont senator is in a three-way tie with Biden and Buttigeig at 23 percent.

In addition, in a series of recent early general election polls, Sanders has shown an ability to beat Trump. An Emerson University survey from mid-December places Sanders at 52 percent over Trump’s 48 percent. A CNN poll from the same time frame indicated similar results, with 49 percent of respondents preferring Sanders to Trump’s 45 percent.

Still, Sanders would have to beat out every other viable contender, several within striking distance of each other in primary polling averages, for the chance to face off against Trump. And as Iowa’s Feb. 3 caucus approaches, multiple sources speculated there are risks in running an electability-based argument against Trump in the midst of the Democratic primary before voters have cast their first ballots.

“The strongest argument against Bernie will be showing that you can defeat Donald Trump,” one Obamaworld source projected. “And he cannot.”