Former Governor Jeb Bush, shown here in New Hampshire in August, is struggling with weak fundraising amid low polling numbers in the 2016 presidential race. (Melina Mara/The Washington Post)

Jeb Bush entered the presidential race as the “shock and awe” candidate whose fundraising dominance was poised to make his campaign an unstoppable juggernaut.

He is not that candidate anymore.

After reporting Thursday that he has less cash in the bank than three other Republican candidates, Bush effectively cemented his status as just another aspirant in a presidential race where the surest predictions have been proven wrong time and again.

Bush — a former Florida governor who relied heavily on his family’s network to amass a $103 million war chest at his allied super PAC earlier this year — announced Thursday that he collected contributions for his actual campaign at a drastically slower pace during a difficult summer.

Bush raised $13.4 million from July to September, and started October with just $10.3 million on hand after spending about $11.5 million — or 86 percent of the total over the quarter. This leaves Bush with less cash in the bank than three opponents, including Sen. Marco Rubio (R-Fla.), whom Bush allies see as his chief rival for GOP establishment support.

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Bush campaign manager Danny Diaz put a positive spin on the figures, writing Thursday in a memorandum to supporters that the campaign was financing a sprawling organization “that we are confident will deliver the Republican nomination and win the White House.”

Fred Zeidman, a major Bush bundler in Houston, said he was pleased, noting that Bush had the second-biggest GOP fundraising haul of the quarter, behind retired neurosurgeon Ben Carson.

“I think that’s a good number, especially when you consider what he raised relative to Marco,” he said. “He has outraised everyone but the flavor of the minute. I think it’s a real good sign.”

But other top Bush supporters viewed the figure as weak considering his family’s national fundraising network, raising fresh concerns after unsteady performances on the campaign trail and polls putting him well behind front-runner Donald Trump.

“He should have hit at least $25 million,” said one major Republican fundraiser, who like others interviewed requested anonymity to speak candidly.

“Some donors are really nervous,” said one top Bush fundraiser. “They think they bought into a winner. . . . Donors want to see him campaign to win.”

Republican presidential candidate Jeb Bush slams Democrats in a video released Oct. 6. (Jeb Bush)

Senior members of Bush’s finance team acknowledged that the campaign has struggled to broaden its network much beyond family loyalists.

“I can tap my Rolodex and my buddies can give money, but we have to have that Malcolm Gladwell ‘tipping point’ where we’re raising money from people we don’t know. We have to scale up,” said Anthony Scaramucci, a hedge-fund manager who joined the Bush campaign after serving as national finance chairman for Wisconsin Gov. Scott Walker’s unsuccessful bid. Still, he said he was confident Bush would be the nominee.

Despite a heavy onslaught of television ads in Iowa and New Hampshire by the pro-Bush super PAC, Right to Rise, his standing in public opinion surveys has remained relatively static or has even fallen.

“The needle hasn’t moved an inch — and he may be worse. That’s what’s scaring folks,” said a second top Bush fundraiser.

“I don’t think Jeb’s getting out of the race, but it’s certainly sinking in that he can’t revive himself just from the ads,” this person added. “He can’t buy his way back. The [poll] numbers are beginning to get hard.The candidate has to have a moment out there, and if that doesn’t happen, I just don’t know.

Right to Rise USA has spent $13 million so far on digital and television ads in early primary states promoting Bush, according to FEC filings. The group has announced plans to spend at least $23 million by the end of year, and reserved another $17 million worth of time in January and February in states like Texas and Virginia with primaries in March.

Bush’s campaign also is advertising on television, putting down $500,000 on a spot in New Hampshire that knocks “D.C. politicians” and “self-promoters.” The campaign announced in September plans to reserve an additional $7.8 million in television time in Iowa, New Hampshire and South Carolina early next year.

Matthew Dowd, a strategist on former president George W. Bush’s campaigns who is unaligned in the 2016 race, said Jeb Bush is banking too much on the power of his super PAC’s advertising.

“Money doesn’t create momentum; momentum creates money,” Dowd said. “We keep saying, ‘Oh, he’s got a super PAC with $100 million!’ But if you don’t have a message that resonates and if you’re not able to have momentum at the big moments, it doesn’t matter how much money you have. It’s not going to solve the problem.”

Dowd added, “They’ve bet on a premise — and maybe it’s the only premise they have, because they have a flawed candidate — that advertising is going to do it, but there’s no evidence that advertising will move his numbers.”

Bush campaign officials are trying to calm the nerves of supporters. A conference call with Bush donors and other supporters Thursday afternoon was described by one listener as brief, upbeat and “insistent that the plan is working.”

The call included brief comments from senior adviser Sally Bradshaw, finance director Heather Larrison and top fundraisers Jack Oliver and Woody Johnson. “The message from the call was, ‘Steady as you go,’” said a second person listening on the call.

The campaign officials, who took no questions, talked about upcoming fundraisers in California and Florida and said they were picking up on positive responses to Bush when voters learn about him from ads or his public events.

After formally launching his campaign in June, Bush raised $11.4 million in his first two weeks, pulling in donations at the hefty rate of $760,000 a day — the fastest pace of all the 2016 contenders, according to an analysis by The Washington Post.

But the pace slowed dramatically the rest of the summer. His campaign averaged just $147,000 a day in the third quarter, despite holding at least 58 fundraising events, according to news reports and invitations compiled by Sunlight’s Political Party Time. George W. Bush did at least three events, and George H.W. Bush did two.

As fundraising ebbed, the Bush campaign took steps in recent months to cut back on its spending. Some staffers took pay cuts, a move first reported in late August by the New York Times and confirmed by Bush campaign officials.

There has been more recent belt-tightening, too, including the candidate taking more commercial flights or driving between events and his traveling encourage staying in cheap hotels, which was reported Thursday.

Rubio, despite raising only $6 million in the third quarter, began this month with nearly $11 million on hand, slightly more than Bush. In a move interpreted as taunting their rival, the Rubio campaign issued a statement Thursday boasting about its “smart budgeting and fiscal discipline” and noting that the candidate flies discount airlines such as Jet Blue and Spirit as opposed to private charter flights.

Ron Kaufman, a Bush supporter and longtime friend and adviser to his father, said, “I think Jeb is not in a great place, obviously, but a good place.”

Kaufman added: “There’s a long way to go, it’s a long slog, and Jeb is built for the long haul. He is not going to win right now, there’s no question about it. But in the end, I think people want someone who’s actually governed something and signed the front of a check, not just the back of a check.”

Tom Hamburger and Sean Sullivan contributed to this report.