“I do have some concerns about Bernie Sanders’ health, considering the fact that he did have a heart attack,” an Iowan says in the Democratic Majority for Israel ad about Sanders, which is backed by a $681,000 TV buy saturating the airwaves in the week before the caucuses. The group, which was formed last year, has not yet disclosed its donors, though it will file a new campaign finance disclosure by Friday.

The ad attacking Sanders represents the riskiest bet yet on the power of big money because of its chance of inflaming Sanders’ fervent fan base. Sanders sent a fundraising email on Tuesday and posted a video for his 10 million Twitter followers: “It’s no secret our campaign is taking on the political establishment and the big money interests who are now running negative ads against us in Iowa. The billionaire class is getting nervous—and they should,” Sanders said. His campaign announced Wednesday it raised $1.3 million online off the news of the ad.

Together, outsiders have dropped more than $14 million in television advertisements, radio ads and other campaigning into the Democratic presidential race, including a pro-Biden super PAC outspending the candidate himself on ads in Iowa, a veterans group supporting Pete Buttigieg in New Hampshire and a nurses union backing Sanders with new advertising in the West.

And the spending surge is likely just getting started. The outside groups expect the candidates running for president will need all the help they can get in the coming weeks in order to compete in the coming slate of ultra-expensive primary contests in the early states and beyond, including the Super Tuesday double-whammy of California and Texas.

The Biden super PAC, Unite the Country, is the biggest spender so far, pumping nearly $5 million in advertising into Iowa. It is now polling and conducting focus groups as it tries to decide where to make its mark next, said Steve Schale, a longtime Democratic strategist who’s now a key adviser to the super PAC.

“Listen, the Democratic nominee is going to be someone who can appeal to a broad swathe of America — and with all good respect to Iowa, that’s not them,” Schale said. “We’re going to begin investing in Nevada in a pretty significant way, and in the next few days making sure we’ve done all the things we can to be helpful in Iowa.”

The “staggering” price tag of airing television ads and running a campaign in the 14 Super Tuesday states will only make it more important for candidates to have huge sums of money, whether it be in their own campaign coffers or from outsiders, after the Iowa caucuses are over, said an Iowa-based political operative.

“If you look at a [Cory] Booker or [Kamala] Harris, they didn’t drop out because they weren’t doing well enough in Iowa, they dropped out because they had zero chance to do anything beyond Iowa. I’m glad Amy Klobuchar is having a few good days but the train does not go on,” the operative said.

So far 27 different organizations have spent money on television ads, mailers or other communications in the Democratic primary, according to the Federal Election Commission. And that count doesn’t include organizations like Our Revolution, the Sanders-founded nonprofit supporting the Vermont senator with on-the-ground organizing, or the Progressive Change Campaign Committee, which does pro-Warren messaging and fundraising, because those efforts aren’t logged with the FEC.

Two leading candidates, Biden and entrepreneur Andrew Yang, have given the go-ahead to single-candidate super PACs that were formed to help them exclusively. While Biden has received several million dollars in spending, Yang is backed by a more modest effort, MATH PAC, which has spent more than $300,000 predominantly on pro-Yang radio ads.

“I do think there’s been, in the progressive community, frustration with super PACs. We don’t disagree with that, we just think Andrew has the best ideas,” said Will Hailer, a Democratic operative running MATH PAC. Most of Yang’s supporters, Hailer also noted, are not in a position to write “massive checks.” But the group is looking ahead and determining which Super Tuesday states to buy more ads in, he said.

Other candidates who did not want help from a dedicated super PAC created to help their candidacies are now receiving outside money in other ways. Buttigieg has benefited from more than half a million dollars in television ads from VoteVets, which supports Democratic veterans running for office. (Buttigieg has disavowed single-candidate super PACs but never went so far as to say a super PAC like VoteVets should not boost his campaign: “I’m not going to get involved in that,” Buttigieg told reporters when asked if he would call on the organization to not spend money on his behalf.)

Sanders will benefit in the coming days from the California Nurses Association spending an initial $260,000 on radio ads in Las Vegas and other pro-Sanders campaigning.

Warren is the only leading candidate who currently does not have any outside groups sending money to air ads on her behalf.

Some of the groups, including the pro-Sanders Our Revolution, do not have to disclose their donors — a fact that has irked opponents, amid an election cycle where there’s a highly charged climate around the way political dollars are raised and spent.

“I do find it ironic that some of the folks who complain about money in politics are running organizations that don’t disclose their donors,” said Schale, of the pro-Biden PAC, which will disclose its donors this Friday. “Let the sunshine in.”