Democrats running for president have spent tens of millions of dollars on complicated voter outreach programs, field staff, and volunteer networks. But as they come down the critical primary stretch, a hard truth has taken hold.

The main thing that is moving the electorate is the national media and there’s not really a close second.

Aides to every major Democratic presidential campaign have told The Daily Beast that they’ve been stunned by the degree to which the conversation taking place on cable and national news has impacted the trajectory of the race. At a time when the party is trying to utilize new mediums to expand its reach beyond the traditional electorate, it’s been the old, stodgy TV press—fed by print reporters-turned-pundits—that has had the biggest tangible impact.

Evidence of that paradigm has been visible since the primary got underway, with candidates shunning media and allowing negative story lines to fester suffering as a consequence and those launching aggressive media campaigns seeing unexpected boosts.

“Pete was completely unknown in Iowa, then he did the CNN town hall, and I remember a week and a half or two weeks later, he was in double digits in Iowa,” recalled Lis Smith, a senior aide to former South Bend Mayor Pete Buttigieg. “And I remember someone sent it to me and I thought it was a typo because I had never seen that sort of movement in an early state based off of national media and one appearance at that. It surprised even me how much that moved the needle.”

National media interest has also provided a late boost to some candidates whose campaigns were virtually written off months earlier.

An aide to Sen. Amy Klobuchar (R-MN) told The Daily Beast that her well-received performance at the New Hampshire debate in February sparked immediate national media interest in the campaign, which contributed to a strong finish in the primary that caught pundits and other campaigns off guard. Following the debate performance, the Minnesota senator’s staff immediately added more events in New Hampshire, booked cable news hits, and expanded the press sections at events due to an exponential bump in media requests.

Sen. Elizabeth Warren (D-MA) was widely perceived to be on electoral life support through last Thursday. And then, a well-received debate performance pumped new blood into her operations. The campaign said it raised $9 million in the three days after the debate and saw its vote share raise more than 50 percent between the early vote and day-of vote in the Nevada caucus.

The dynamic has had a number of side-effects, including creating incentive structures for sputtering campaigns to stick around for the next big moment and sparking a mad—somewhat recent—scramble to get candidates on TV. Not everyone is particularly pleased by it, arguing that it is propping up more centrist-minded, conventional wisdom-spouting candidates that should otherwise be failing.

“ There’s a group of a dozen cable news executives, mostly white and mostly male, who have a big role in deciding the trajectory of the Democratic primary,” said one top aide to a presidential campaign. “They decide who wins and who loses debates. They decide who gets to sit on panels talking about who wins and loses the debates. They decide guests, chyrons, narratives, who gets airtime and who doesn’t. It can be frustrating but they are usually the last to understand the reality of what’s happening on the ground.”

Reasons as to why cable and broadcast news are having an outsized impact vary. But in conversations with operatives on and off campaigns, two main theories are offered. The first is that much of the primary debate has been waged around an inherently subjective concept: which candidate is the most electable. And that, in turn, has compelled voters to turn to pundits for signals about how they should digest the race. Warren’s fall in the polls, several campaign operatives noted, corresponded closely with national media chatter about her electability—both tied to her embrace of Medicare for All and a high-profile New York Times poll of swing states that showed her faring worse against Donald Trump than her main competitors.

But the larger explanation for the trend is likely how the structures of media are changing themselves, with social media allowing even passive observers of politics to have political news pumped into their media feeds by engaged partisans.

“From 2008 through 2012 there was this giant chasm between the things people engaged in politics cared about and what the rest of the country was aware of. We would constantly do focus groups in the ‘08 campaign where D.C. was in a tizzy about a faux scandal du jour and you would go ask persuadable voters and they’d have no idea what we were talking about,” said Dan Pfeiffer, Barack Obama’s former communications director. “Some time around 2013, I remember the IRS faux scandal popped up and believing it was highly unlikely that voters would care about it. And we went and did focus group and they knew all about it. And most alarming was they knew about it from a conservative view. It was the first hint that Facebook was tilting the distribution of information in a conservative direction.”

Pfeiffer, who discusses the phenomenon in his new book Un-Trumping America, worked for campaigns that famously eschewed cable news-driven narratives and controversies. Today, many of those campaign figures are pundits themselves, running popular national podcasts (Pod Save America) or making appearances on CNN (David Axelrod) or MSNBC (David Plouffe and Robert Gibbs) to wax about the state of the current presidential race.

The candidates themselves, meanwhile, have become ubiquitous on television in ways that—seasoned operatives say—are reminiscent of how Donald Trump used the medium to catapult his own primary bid four years prior.

Despite his campaign’s frequent criticisms about the national media, Sanders has continued to participate in a bevy of nationally televised interviews. According to his campaign, the Vermont senator did 20 national media hits between Feb. 6 and Feb. 14. But he’s remained selective about his appearances—the senator rarely joins other Democratic candidates in the “spin room” after debates and has repeatedly declined post-debate interviews with the cable news networks. His aides try and book him during news cycles that play to his strengths and, because he’s so sought after, he gravitates more towards national news over cable. On Sunday, for example, he appeared on CBS’ 60 Minutes.

Other candidates have not had the luxury of choosing where they can go and, instead, have embraced a flood-the-zone approach.

Buttigieg did nearly double the number of hits as Sanders during that same week around the New Hampshire primary. Warren, fresh off her debate performance, immediately hit several television networks, and expanded on her viral debate moment—demanding that former New York Mayor Michael Bloomberg release women who worked for him from their NDAs—during a CNN town hall on Thursday (she has another scheduled for later this week).

Both former Vice President Joe Biden and Bloomberg have altered their media strategies in the past several weeks. After shunning national interviews for much of the campaign, Biden began appearing on the Sunday shows in February—ABC’s This Week on Feb. 9 and Meet The Press on Feb. 16, Face the Nation on the 23rd, and Kasie Hunt’s MSNBC show later that day. He’s also remained active on daytime television, appearing on The View and Nicole Wallace’s afternoon MSNBC program. According to one person familiar with Biden campaign strategy, the former vice president is banking on a strong showing in South Carolina to help drive a national media comeback narrative that will propel him past Bloomberg and other “moderate” candidates.

Network insiders told The Daily Beast that Bloomberg’s team initially refused numerous offers for major interviews and televised town halls leading up to his Nevada debate, which was widely panned. But after attempting to substitute national media appearances with nearly endless TV advertisements, his team seems to be coming to the same realization that national media narrative is the primary mover this cycle. They hastily scheduled a CNN Town Hall for this week—though he has since pushed it back two days.

“A lot of candidates have hoped or tried to bypass the national media using things like social media,” one cable news executive said. “Everyone who has tried to do that has been unsuccessful. It's not a winning strategy.”