Democratic presidential candidate Hillary Rodham Clinton greets audience members after a community forum in Des Moines this month. (AP Photo/Charlie Neibergall)

This post has been updated.

Democratic presidential contender Hillary Rodham Clinton raced through millions of dollars over the summer as she expanded her campaign’s ground operations and launched a paid television campaign, spending around nine out of every 10 dollars she raised in the third quarter.

Clinton pulled in more than $28 million and spent an estimated $24.8 million, for a burn rate of about 88.7 percent, based on early numbers released by her campaign. As of Sept. 30, she still had more than $32 million on hand, campaign spokesman Josh Schwerin said in a tweet Thursday.

That gives her a small financial cushion over Sen. Bernie Sanders (I-Vt.), who raised $26 million and had $26.5 million left in the bank heading into October. But Sanders only spent an estimated $11.6 million -- less than one out of every two dollars he raised -- showing how far he has been able to take his insurgent bid with a relatively lean operation.

[Sanders nearly matches Clinton in fundraising for third quarter]

“What it tells us is that Bernie has financial staying power,” said Jeff Weaver, Sanders’ campaign manager. “We have the financial wherewithal that will allow for a major campaign through Iowa, New Hampshire, South Carolina, Nevada and beyond in state-by-state, delegate-by-delegate contests for the Democratic Party nomination.”

The senator from Vermont has recruited volunteers to do much of his on-the-ground organizing instead of paid staff. He holds events in a range of large-capacity spaces, from middle school gyms to basketball arenas, usually decorated only with an American flag or large campaign sign. He has also incurred minimal fundraising costs by relying on an army of small donors who given him money online. About 99 percent of his donations were for $100 or less, campaign officials said.

Sanders flies coach and is usually accompanied by two or three aides, who often travel together on the ground in borrowed cars. When he's in New Hampshire, one of his sons, who lives there, often drives him around.

The senator has also not yet begun running TV ads, while Clinton launched her first spots in Iowa and New Hampshire in August. She will have spent $6.2 million on airtime by the end of October.

She also has more offices and more paid staff than any other 2016 candidate of either party. Most of them are based in New Hampshire and Iowa, where she has 17 field offices. Her Brooklyn headquarters also thrums with scores of paid staffers.

Clinton has stuck to a campaign strategy of policy rollouts roughly once a week, accompanied by town hall-style organizing events held in school gymnasiums or similar venues. By design, the events typically draw a crowd of a few hundred -- nothing like the mega-rallies Sanders holds.

Keeping things intentionally small avoids a direct comparison with Sanders’s impressive ground organizing operation, much of it done on a shoestring. But the intimate events, at which Clinton frequently takes audience questions, also serve to point out how much Clinton is spending on fairly basic day-to-day operations.

Her road events in New Hampshire and Iowa are not obviously lavish. Accoutrements rarely go beyond folding chairs, taped-up campaign signs and cases of water. But behind-the-scenes, there are large numbers of staffers and a hefty cost of private plane travel for Clinton and her small circle of aides. Clinton is using a rented jet almost exclusively these days, and flying several days a week for both public events and private fund-raising parties.

Her campaign has also invested far more than Sanders in putting on high-dollar fundraising events, holding nearly 60 such receptions over the last quarter.

Clinton’s rapid spending rate and Sanders’s ability to nearly match her fundraising haul last quarter raised new questions about the financial advantage she was expected to have in the primary contest. Her third-quarter total surprised some top campaign bundlers, who had been assured by senior Clinton aides that the campaign was meeting its goals. Some assumed that meant that she would bring in an amount closer to the record-setting $47.5 million she collected in the spring.

The Clinton campaign sent a video message to supporters on Thursday evening touting the latest figure. Campaign manager Robby Mook tells supporters the campaign has signed up 64,000 active volunteers and is operating in every congressional district. He never mentions polls or hints at any setback, although he tells supporters to prepare for a hard election.

"Winning campaigns have a strategy and stick to it," Mook says. "So we are going to stay on strategy no matter what the other side throws at us."

The tight money race has further mobilized supporters of Vice President Joe Biden, who pointed to the drop in Clinton’s fundraising as a sign that there is ample room for him to get in the race, even at this late date.

“I think it creates a lot more space,” said one major party fundraiser who is helping corral support for a possible Biden bid and requested anonymity to describe private conversations.

[Possible Biden run puts Obama fundraising network on high alert]

Clinton backers shrugged off the idea that her fundraising indicated that enthusiasm for her bid was dwindling. They noted that she has raised $75 million so far, well on her way to meet her $100 million goal for the end of the year.

“It's a terrific result for Hillary,” said Chicago businessman J.B. Pritzker, a major Clinton fundraiser. “This is the most any non-incumbent has raised at this point in a presidential campaign.”

There were also signs that some of her supporters are agitating for a direct engagement with Sanders, which Clinton has said she will not do.

Florida donor John Morgan suggested that Clinton should contrast her more middle-of-the-road policy prescriptions with his far-left ones.

“Sanders’s numbers are good, but everyone has been afraid to point out why Sanders can't win,” Morgan wrote in an email. “We all like what he is saying because it feels so good," he added. “Fifteen bucks an hour? Great!” he said, referring to Sanders’s recommended minimum wage. “Redistribute the wealth? How?”

[How Bernie Sanders would transform the nation]

Clinton should not be afraid to note that Sanders is a self-described democratic socialist, Morgan said.

“Socialism works when you have us guarding you,” Morgan said, referring to the United States military. “You can't give away the farm on social programs and be the No. 1 super power in the world.”

John Wagner contributed to this report.