Jeb Bush’s donors complain he is “burning money” with lavish spending on fancy hotels, fundraisers at the Four Seasons and St. Regis, and private planes – all while his poll numbers have plummeted and some GOP operatives are wondering whether he should remain in the race.

The federal filings of both Bush’s campaign and Super PAC Right to Rise show his campaign has at times been “a whirl of private planes and high-end affairs,” according to Reuters, which received responses from 11 of the 16 major donors to Bush’s campaign it contacted to inquire whether the money contributed has been well spent.

When questioned about Bush’s spending, all the major donors who responded asked for anonymity.

“There is no return on investment on the Bush ad buys, zero,” said one high-dollar donor.

“They are burning money,” said a second major donor, who asked not to be named for fear of displeasing the Bush family.

“Look, this is not the election cycle to be spending like a silver-spoon establishment candidate,” a third donor said. “It just doesn’t look right,” said the donor pointing to the prominent issue of income inequality.

Bush spokeswoman Kristy Campbell fired back at the criticism.

“We are running a national campaign that is competing everywhere, and we have made investments that have allowed us to do what serious campaigns must do to be competitive in the primary and general elections,” she countered.

Though Bush’s spending has increased to more than $80 million as of this month, his poll numbers have been below the 10 percent mark since last October. Many watching the race have observed Bush’s support for amnesty for illegal immigrants and the highly unpopular Common Core standards have led to his decline in the polls.

According to the report, ad-tracking firm SMG Delta says that Bush’s campaign has spent significantly more than those of Donald Trump ($5 million), Sen. Ted Cruz ($11 million) and Sen. Marco Rubio ($49 million).

Campaign finance reports show, for example, that between June and September, Bush spent $1.2 million on private planes, while Cruz spent $158,000 and Rubio spent $293,000. Frontrunner and real estate developer Donald Trump travels in his own Boeing 757.

The news report contrasts the spending of Bush with that of Cruz, who “favors cheaper accommodation options like Holiday Inn and often flies on budget carriers…”

Similarly, spending on high-end hotels is 70 percent of Bush’s overall hotel spending, while Cruz’s proportion is about 56 percent and Rubio’s 61 percent. Trump reportedly flies home nearly every night.

Additionally, Bush spent over $400,000 on rent for facilities and catering at high-end venues such as the Union League Club, while Cruz spent $185,000 and Rubio $265,000 on similar venues.

On Sunday, the latest campaign finance reports are due, and donors will learn how much has been spent.

Charlie Spies, counsel for Right to Rise, said high-price venues are standard for the donor world.

“If you can hold an event at a fancy hotel and raise millions, then it’s well worth holding it at a swanky hotel,” he said, indicating that the super PAC had negotiated “below market” fees with vendors and hotels.

Still, Bush has outspent Cruz and Rubio on staff and consultants. Beginning in the spring, Bush spent about $8 million, while Cruz spent $2 million, and Rubio slightly below $2 million. Trump spent about $1.7 million.

“Overall, Trump, Cruz, and Rubio have spent a small fraction of the $82 million Bush has reported paying out,” Reuters observes. “Cruz spent $18.5 million and Rubio outlayed $32 million, according to the filings made so far.”

Nevertheless Ambassador Jeanne Phillips – a member of the Right to Rise governance committee – suggested the criticism that Bush is blowing his campaign war chest is “ridiculous.”

“I’ve known Jeb for 30 years, so the idea that Jeb would allow anyone around him to be frivolous with money is hilarious — it’s ridiculous,” she said. “The man is the most conservative, fiscally responsible person I’ve ever worked with.”