The roster of celebrity surrogates is designed to bring out young and unlikely voters to events: A Friday rally featuring Ocasio-Cortez and Moore, which Sanders couldn’t attend because he was in Washington for the impeachment trial, drew an estimated 800-plus people. Overall, nearly 6,000 attended events in Iowa held by Sanders, Ocasio-Cortez and Moore over the last few days, according to the campaign.

Their support comes after the Sanders team courted backing from people such as rapper Cardi B and other stars of color for months.

But the high-profile allies come with risks: Ocasio-Cortez, for instance, is seen as divisive and too far left by some moderate and conservative Democrats. And the youthful edginess of many of Sanders’ celebrity fans likely won’t connect with the senior voters with whom he struggles.

Even so, the senator’s supporters say, the voter turnout potential of his traveling political festival far outweighs the drawbacks.

“I think these folks are getting behind him because we all have one common goal: Defeat Donald Trump,” said U.S. Rep. Mark Pocan, the co-chair of the Congressional Progressive Caucus who campaigned alongside Ocasio-Cortez and Moore over the weekend. “Be it indie rock bands or documentarians or progressive members of Congress, we know that the only way to defeat Trump’s faux populism is real populism, a movement supported by a wide coalition of people that promises to work for the millions of Americans that have been ignored or overlooked by our political system.”

In the beginning of the primary, the Sanders team made a big bet: To win, they would need to expand the electorate to include more young, Latino, and working-class voters. Jeff Link, an Iowa-based Democratic strategist, said the famous surrogates Sanders is deploying during the final sprint through Iowa appear to be aimed at that same end-goal.

“It kind of feels like they are trying to expand the typical caucus-goer universe by bringing people who are not typical political surrogates,” he said. “If there is an unexpected turnout, it’s probably good for him, so I think that’s probably a good strategy.”

Sanders has made a concerted effort to win support from certain celebrities. He met with mostly black and Latino musicians, writers and social media personalities at a private lunch in Hollywood over the summer. He also spoke with Cardi B on the phone or in person a handful of times last year, including at critical moments such as in the hours before one Democratic debate.

Sanders’ rallies often include performances by bands, and last weekend’s events were no different: Mike Posner and Portugal. The Man played at them.

“Look, Bernie Sanders is someone who believes in a link between culture and politics,” said Ari Rabin-Havt, Sanders’ deputy campaign manager. “Bernie believes that events should have more than a speech — that you should bring people in, they should have fun, there should be energy and excitement and enthusiasm. And music helps do that.”

At times, Sanders’ penchant for winning over celebrities has come with downsides. The Vermont senator faced blowback when his campaign posted a video on Twitter last week highlighting podcast star Joe Rogan saying he will “probably vote for Bernie.”

Rogan is not campaigning for Sanders like Moore and others. But the liberal organization MoveOn accused the Sanders campaign of “bolstering the endorsement of someone known for promoting transphobia, homophobia, Islamophobia, racism and misogyny.” The Human Rights Campaign said Sanders “must reconsider this endorsement.”

Briahna Joy Gray, Sanders’ national press secretary, said in a statement that "the goal of our campaign is to build a multi-racial, multi-generational movement that is large enough to defeat Donald Trump” and “sharing a big tent requires including those who do not share every one of our beliefs, while always making clear that we will never compromise our values.”

It’s unclear what, if any, impact Rogan’s endorsement will have in Iowa. Several residents interviewed over the weekend were not aware of it, and two who had followed the news said they were not bothered by the fact that he was backing Sanders. One Sanders volunteer, meanwhile, said some Iowans said they were supporting him after listening to his interview with Rogan.

Elizabeth Warren has also displayed an ability to win over celebrity supporters. “Queer Eye” host Jonathan Van Ness campaigned for her over the weekend in Iowa. Actress and musician Mandy Moore stumped for Pete Buttigieg in the first-in-the-nation caucus state earlier this month.

When Ocasio-Cortez first campaigned for Sanders in Iowa in November, Scott Punteney, leader of the Pottawattamie County Democratic Party, said her ideas “might not sit well” with moderate Democrats. With a week to go until the caucuses, though, he said it’s less clear what effect her campaigning will have.

“I don’t know if it’s a positive or negative at this point,” he said, adding it’s similarly difficult to predict how Sanders will perform on Feb. 3. “It’s hard to gauge with him because many of his supporters are independents or have not been strong party activists. It’s harder to measure.”

Sanders’ opponents think Ocasio-Cortez and other surrogates from the so-called "Squad" hurt his case. “Maybe Gov. Cynthia Nixon can join these members from tough-to-win districts and also talk about how to kill thousands of Iowa jobs,” said a person in a rival campaign, referring to the progressive actress who unsuccessfully challenged New York Gov. Andrew Cuomo in 2018. "Keeping the House and winning the Senate flows through Queens.”

Some people who went to a Sanders campaign town hall in Cedar Falls, which Sanders did not attend, said they came out specifically to see Ocasio-Cortez.

"Moderate voters are not in the calculus for the Sanders campaign for the next week,” said Link. "They are trying to remind their base and progressives that he’s the right one.”