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MIAMI (CBSMiami/AP) — Coming in a close to third to Donald Trump’s second place finish in the Iowa caucus has opened the donor floodgates for Senator Marco Rubio.

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For months, many of these benefactors have been sitting on their wallets or spreading their money around to multiple presidential candidates as they waited to see if one could rise up to take on Trump and conservative insurgent Ted Cruz.

Rubio, who picked up the same number of Iowa delegates as Trump, and just one fewer than Cruz, surprised many considering the billionaire real estate moguls dominance in the polls.

“A lot of people who held back have now seen how real my candidate is,” said Phil Rosen, a New York-based fundraiser for Rubio.

Rosen said he’d received — unprompted — about 20 emails in the early hours Tuesday from people asking how they can give money to Rubio’s campaign.

But as Rubio experiences an upswing, Jeb Bush is falling out of favor with key donors which could eventually swing more money toward his former protege.

Bush commanded an enormous early fundraising advantage through an outside group known as a super political action committee. The investment has not paid off as Bush has lagged in many early state polls and finished under 3 percent in Iowa. That’s had a chilling effect on big donors, said Frank VanderSloot, an Idaho billionaire who backs Rubio.

“Everyone I talk to, my friends at the U.S. Chamber of Commerce, other members of the business community, they really like Marco Rubio. But I think they got burned with Jeb,” VanderSloot said. “They were taken on so many twists and turns — they’re still waiting to make sure that doesn’t happen again.”

Billionaire Minnesota broadcast executive Stanley Hubbard is Exhibit A. He’d previously expressed interest in giving heavily to groups helping Bush, Rubio or another GOP contender who can beat Trump and Cruz. But he’s part of what VanderSloot called “a lot of money still on the sidelines.”

Hubbard said he’ll wait until after New Hampshire, where it’s possible New Jersey Gov. Chris Christie or Ohio Gov. John Kasich could have a solid showing, before putting big money into 2016.

However, Hubbard has reached one conclusion: “It’s too late for Jeb Bush, and I think that’s kind of sad.”

One of Bush’s biggest boosters, Mike Fernandez, also said he was “saddened” that his did poorly in Iowa. Fernandez gave more than $3 million last year to an outside group backing Bush and separately paid for anti-Trump advertisements.

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“I hope somehow he makes a miraculous comeback,” the billionaire Miami health-care executive said of Bush. “There’s obviously a disconnect between his campaign and what the people want.”

Asked if he would consider backing a candidate other than Bush, he said, “I’m going to stay by his side until the very end.”

Any donor momentum Rubio gains out of Iowa would build on efforts that seemed to be beginning late last year, fundraising reports filed Sunday night show.

He was the standout fundraiser among Bush, Christie and Kasich, the foursome that are vying for many of the same voters and donors. In the final three months of the year, Rubio roughly doubled what Bush had raised, even though Bush inherited a network of support from his father and brother, both former presidents.

Rubio dramatically outraised Christie and Kasich and began January with more cash on hand that any of those three, although his $10.4 million fell short of the $18.7 million Cruz had on hand.

Cruz eagerly noted that financial advantage as evidence he’s the GOP candidate to beat.

“It’s, frankly, unprecedented,” Cruz told reporters Tuesday night on a flight from New Hampshire to South Carolina. “The conservative is supposed to be broke, and instead we’ve got the resources to compete nationally combined with a grassroots army from the ground.”

Looking specifically at clusters of donors that make up the Republican Party “establishment” — power centers on Wall Street in New York and K Street in Washington — Rubio is increasingly dominant.

Rubio’s campaign reported more than $1 million that was raised by registered Washington lobbyists in the second half of 2015 — more than double what that group of people raised for Bush in the same time period.

Christie and Kasich raised barely anything via Washington lobbyists, the reports showed.

Two hedge fund billionaires, Paul Singer in New York and Ken Griffin in Chicago, gave Rubio-boosting super PAC Conservative Solutions $2.5 million each late last year. Chris Cline, a billionaire coal executive, gave $1 million to the Bush super PAC Right to Rise through one of his limited liability companies. Four months later he wrote a personal check for $500,000 to Conservative Solutions.

Cline called both Bush and Rubio “excellent candidates” — but added, “Rubio is obviously a strong candidate.”

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