Sanders held $33.7 million cash on hand on his third-quarter fundraising report. Warren had $25.7 million during the same period, while South Bend, Indiana, Mayor Pete Buttigieg came next $23.3 million.
Biden, meanwhile, held just $8.9 million, a small fraction of what his leading rivals have at their disposal.
With the first votes of the Democratic contest just months away, the candidates are entering a critical and expensive period when having an ample supply of cash can make or break a campaign. Biden's total raises questions about his durability as a front-runner.
"Can he do better at fundraising? Absolutely. And I think he will," said Biden donor and fundraiser Steve Westly.
While many contenders in the crowded field will be triaging resources and making difficult spending decisions in the coming months, the advantage enjoyed by the Vermont and Massachusetts senators means they will have the luxury of spending when and where they want. That will allow them to buy large amounts of advertising, respond to attacks and boost their ground games in early voting states like Iowa, New Hampshire and South Carolina.
"If you are sitting at fourth, fifth or even seventh place and you don't have the money to have a real paid media campaign, the future for you is probably pretty bleak. You will get drowned out by the rest of the noise," said Grant Woodard, a Des Moines attorney who is a veteran of John Kerry's and Hillary Clinton's Iowa campaigns. "It's still a fluid race. But to be competitive in this thing you are going to have to be on TV, digital and you are going to have to be on direct mail. The fundamentals still matter."
Biden has built a formidable campaign, but it's come at a cost. The $17.6 million he spent over the past three months was more than the $15.7 million he took in, according to his fundraising figures that were submitted to the Federal Election Commission on Tuesday's reporting deadline.
Despite his lackluster totals, he still remains a favored candidate in recent public opinion polls, along with Warren. And in recent weeks, both Biden and his wife, Jill, have kept up a busier fundraising schedule.
"People focused on the minutia and the details," said Westly, a Silicon Valley venture capitalist. "The reality is this is quickly boiling down to a two-person race - and that's between Joe Biden and Elizabeth Warren."
Still, Biden is not alone in the sprawling field.
California Sen. Kamala Harris had $10.5 million cash on hand but deferred paying consultants including her pollster nearly $1 million, records show. New Jersey Sen. Cory Booker held $4.2 million, disclosures show.
And the situation was far more dismal for others. Former Obama housing secretary Julián Castro had just $672,000 cash on hand, while Ohio Rep. Tim Ryan had even less, $158,000, records show.
The advantage Warren and Sanders have was evident in the way they have been able to spend.
Sanders' $21.5 million in spending between July and the end of September topped the list. It enabled him to spend $3.8 million on advertising and online fundraising, drop nearly $1 million on campaign merchandise and pay his staff a combined $5.6 million, records show.
Warren's $18.6 million in spending during that period allowed her to fund a sprawling staff operation that includes well over 500 people on the payroll, in addition to financing a more than $3.2 million digital operation, records show.
Buttigieg, too, has hired roughly 100 staffers in Iowa, where his campaign is betting on a strong performance.
But just because they have a massive cash advantage doesn't mean the other candidates are doomed. Even though time is running out, candidates could still see their financial picture improve, particularly if they have a viral online moment to boost their online fundraising.
"The question is: Do you have enough money to run a strong campaign? North of $5 million and you have the ability to get through the fourth quarter," said Democratic donor and Wall Street financier Robert Wolf, who was an economic adviser to Barack Obama.
Copyright 2019 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.