Las Vegas (CNN) In the unsparing judgment of the Twittersphere, there was one clear loser after Jeb's Bush's graceful exit from the Republican presidential race Saturday night: political strategist Mike Murphy and the Bush-allied super PAC Right to Rise USA, which he directed.

Murphy has long been one of Bush's closest advisers -- and the political world was in awe last year when Right to Rise raised $100 million just as Bush was launching his candidacy.

Now, the super PAC will go down in history as yet another failed Murphy juggernaut.

In the armchair quarterbacking following Bush's departure from the race Saturday night, Murphy is facing countless questions about the efficacy of the PAC spending tens of millions of dollars on a candidacy that floundered months ago and never rebounded.

Murphy said in an email Monday, "Out of more than 11,000 donors only a handful have complained."

"This is just axe grinding, mostly from rival consultant types," Murphy said.

Murphy's failed effort to help Bush follows his strategic oversight of another expensive losing campaign: the $177 million effort of 2010 California gubernatorial candidate Meg Whitman. Despite her campaign's lavish spending, Whitman lost to Democrat Jerry Brown, who spent a mere $36 million by comparison.

For months now, there have been rumblings of dissatisfaction among Bush donors about the strategic decisions made by Murphy at Right to Rise.

Republican strategist Mike Murphy speaks during a taping of "Meet the Press" at the NBC studios March 2, 2008, in Washington.

Some were puzzled by the super PAC's decision to emphasize Bush's government experience in a year when voters clearly were looking for outsider cred and a candidate who could channel anger at the establishment.

Right to Rise also angered some of its own donors by targeting Florida Sen. Marco Rubio, who could well become the Republican Party's nominee.

Twitterstorm

As Bush bowed out Saturday evening after a disappointing fourth-place finish in South Carolina , Murphy came under a hail of criticism on Twitter -- with adversaries mocking the lavish spending by "Right to Rise" compared with Bush's performance in the early primary states.

One Bush bundler told CNN's Dana Bash that when it came to Murphy, "strong knives are out."

"He made minimum of $14 million," the bundler said, requesting anonymity to speak freely about campaign strategy.

The details of Murphy's compensation package at Right to Rise are not publicly known. Murphy responded to the $14-million figure by calling it, "Absolute bulls---."

"That mystery donor should have the guts to call me and get straightened out," Murphy said in an email Monday.

Charlie Spies, the attorney and treasurer for the Bush-allied super PAC Right to Rise, said the Bush bundler's characterization was wildly inaccurate.

'Wildly wrong'

"That amount is wildly wrong, not even in the ballpark of what Mike's potential compensation could have been," said Spies. "We put vendor per vendor compensation caps in place to ensure that nobody made more than a certain amount of money. That amount is confidential, as is standard for most contracts; we have confidentiality provisions."

Refuting the anonymous bundler's assertion, Spies added that "there is no way any so-called bundler would have any idea how much any vendor was making. The only people who would have any way of knowing that are the vendor themselves, myself as a treasurer and counselor, or our governance committee, which is a three person committee of senior donors and political leaders that was put in place to make sure that all compensation was reasonable and something donors would be comfortable with."

The governance board of the Right to Rise super PAC, Spies said, approved the budget as well as individual components of the budget, including potential compensation.

Murphy's company did receive payments for "a very small piece of ad buys, but that counts toward the overall compensation cap," Spies said. "The percentage that his firm was paid is the lowest I have ever seen for a similar deal.... Because we had hoped and expected to be successful and raise and spend a lot of money,— on top of the low percentage, we put an overall cap in place to ensure that there wouldn't be a windfall of compensation for any vendor if we raised and spent $500 million," Spies said.

Spies said he was not at liberty to disclose compensation cap for Murphy and his company.

Murphy was handsomely paid by Whitman's campaign during the 2010 gubernatorial race. Whitman invested $1 million in a movie company that he owned before he had even joined her effort. Most months after he joined her campaign, Murphy's company, Bonaparte Films, was paid $90,000, according to financial disclosure reports filed in California.

But Republican strategist Rob Stutzman, who was supportive of Bush's candidacy and has worked with Murphy in the past, said the super PAC's spending ought to be viewed within the context of a wild and unpredictable presidential cycle.

"We've seen the diminished value of TV advertising," Stutzman said, noting that Donald Trump has been able to draw attention and free publicity largely through earned media news coverage this cycle. "Second, Jeb was already a very well-defined candidate to voters and there wasn't a lot of new information for them to work with."

Bush, Stutzman said, "was obviously in a category of candidates that is out of favor with voters this election cycle. All of the money in the world is not going to bend the reality of what voters have an appetite for."

Right to Rise said in a statement Saturday night that it is ceasing its activities "in support of Governor Bush's nomination."

"We could not be more proud of Jeb Bush, the campaign he ran, and the hopeful and optimistic message of conservative reform that he communicated throughout this primary," the Right to Rise statement said. "Our team is grateful to the more than 11,000 Jeb Bush supporters who helped us in our efforts."

But other candidates criticized the negative tactics of Right to Rise in the early primary states where they targeted not just Rubio, but other GOP rivals like Ohio Gov. John Kasich.

"Their super PAC ran a tough campaign, they ran a lot of negative ads," Kasich strategist John Weaver said. "We had to disavow some of the things that our super PAC ran, so I'm sure that Jeb Bush -- I wouldn't speak for him, clearly -- might do things differently if he was in control of his super PAC. I have no idea."

UPDATE: This story has been updated to reflect comment from Mike Murphy and Charlie Spies refuting a characterization of Murphy's compensation that he described as "completely inaccurate."