The financial edge enjoyed by Sanders, Warren and Buttigieg is already translating into tactical advantages: Warren paid salaries to over 600 staffers over the summer, while Sanders approached that number, dwarfing the rest of the field. Buttigieg dropped $4.7 million on just digital ads last quarter, while also airing TV ads in Iowa and New Hampshire.

That built-up cash — and the freedom to spend big leading up to Democratic primary voting — is “enormously important, and I’d argue, more important than what you raised,” said former Vermont Gov. Howard Dean, a 2004 presidential candidate. “Cash is the biggest, most important metric that tells us who can really compete and who can’t.”

Sanders leads the field in cash on hand with $33.7 million, followed by Warren with $25.7 million. But after Buttigieg ($23.4 million), there is a steep drop-off to the next highest campaign account. Harris has $10.5 million on hand, followed by Biden. No other Democrat had more than $7 million in the bank at the end of the third quarter, and most of them are already spending faster than they are raising money — without even running a major TV ad campaign yet.

Outside the top candidates, the cash crunch puts pressure on an already shrinking field to narrow further. Some candidates, assuming fundraising would be better, “built a house they can’t pay for” in the early states, said Doug Herman, a Democratic consultant who is unaffiliated in the presidential primary.

“It leaves them with enough money to continue, but not enough money to change anything about their future,” Herman said. “They won’t have the ad budgets for when it matters.”

Indeed, former Housing and Urban Development Secretary Julián Castro burned 91 percent of the money he raised in the third quarter, leaving him with just $670,000 in the bank. Former Rep. Beto O’Rourke used up 81 percent of his total and has $3.3 million left over, while Sen. Amy Klobuchar burned 79 percent of hers, leaving just $3.7 million in the bank. None of the three has qualified yet for the next Democratic debate in November.

“With so many candidates in this race, making it so much more difficult to have a breakout moment, money in the bank is even more important than ever before,” said Sean Bagniewski, Polk County Democratic Party chairman.

Failure to break out of the pack already proved lethal for a handful of candidates during the third quarter. Sen. Kirsten Gillibrand, Washington Gov. Jay Inslee, Rep. Seth Moulton, Rep. Eric Swalwell and New York City Mayor Bill de Blasio all dropped out of the presidential race last quarter, and their financial reports show that many of them simply ran out of money while trying to make a splash in the crowded 2020 election.

“Polling and money go hand in hand because candidates who are out front raising the most money are polling the best, which then helps them raise more money,” said Jefrey Pollock, a Democratic pollster who advised Gillibrand’s presidential campaign. “That’s usually the case, but it’s particularly true this cycle, and it makes breaking into that top tier extremely difficult — even more so this late into it.”

Fundraising isn’t a problem for the quarter’s biggest spender, billionaire Tom Steyer, who spent $47 million on his bid, almost entirely from his own bank account.

Businessman Andrew Yang also stood out in his fundraising haul, bringing in nearly $10 million last quarter, easily topping some longtime members of Congress. He’s sitting on $6.8 million in cash on hand.

The quarterly filings also cast new light on an ongoing debate within the Democratic Party about how candidates should raise money, and from whom. Earlier this week, Warren attacked her Democratic rivals for “hobnobbing with the rich” and called on them to publicly disclose their bundlers and their private fundraising schedules.

Warren and Sanders have both eschewed traditional high-dollar private fundraising events, and Warren recently pledged to no longer accept contributions over $200 from executives at “big tech companies, big banks, private equity firms or hedge funds.” Warren and Sanders haven’t suffered from their decision to reject traditional fundraising in the primary, relying instead on high-octane online fundraising. But Buttigieg warned that Democrats can’t beat President Donald Trump “with pocket change” and the party needs “the full spectrum of support in order to compete.”

But Sanders and Warren’s online success is a measure of where the party is going, said Bagniewski. “If I had to pick between ActBlue and the DNC’s megadonor list, I’d pick ActBlue every time,” adding that the small-dollar fundraising platform “has fundamentally changed the way we can raise money.”

Buttigieg has also raised significant money online, but he, Biden and Harris have all leaned on high-dollar donors, too, frequently appearing at private fundraising events.

As Biden’s campaign spending picked up over the summer, his reliance on maximum donors — who can only give once and are not a renewable campaign resource — meant that his fundraising could not keep pace. More than one-third of Biden’s contributions came from maximum donors in the second quarter, and max-out donors comprised a similar portion of a smaller pie for Biden this quarter.

But Biden’s campaign did appear to get a fundraising lift in the final 11 days of the quarter, after news broke Sept. 20 of a whistleblower complaint alleging that President Donald Trump improperly pressured Ukraine into investigating Biden and his son. The Biden campaign responded by fundraising aggressively off of the scandal, more than doubling its previous daily average donation total.

As the field narrows, Buttigieg’s campaign is already eying bundlers for other candidates. On a call with members of its “investors circle” last week, Buttigieg staffers urged its top donors to start wooing bundlers for other campaigns, particularly those languishing in single digits, according to a Buttigieg donor.

“Right now, money is more important criteria for a candidate than your poll standing,” Herman said. “You can change your poll standing with money, and you can’t without it.”

Marc Caputo, Maggie Severns and Zach Montellaro contributed reporting.