They turned to David Brock, who crusaded for the Clinton family during the days of impeachment and scandal in the 1990s.

Clinton’s new inner circle privately called him a “nut bar” and “soulless narcissist,” a wild-eyed mercenary from the old Clinton wars who could be unpredictable. But Brock’s skills in the political dark arts positioned him to hunt down a copy of the book, “Clinton Cash,” before it was on sale.

“Feels like what Brock is good at,” John Podesta, now the campaign chairman, emailed Robby Mook, who would become the campaign manager. “Great idea,” Mook replied. Brock’s team delivered.

As Clinton aims to move back into the White House, the cottage industry around her political aspirations has sprung up anew and created tensions along the way. Tapping a deep network of donors and their own appetites for bloody political combat, eccentric operatives earn handsome livings orbiting in Clinton’s universe and even work within the shadowy corners of her campaign, according to interviews, tax and campaign filings and hacked emails from Podesta’s inbox posted on WikiLeaks.

Chief among these operatives is Brock, the former right-wing antagonist who now commands a network of political groups that will raise about $65 million to elect Clinton and other Democrats this cycle. The groups have paid generous salaries to him and others, including millions of dollars in commissions to a fundraiser who has summered with Brock in the Hamptons.

Over the months of this long campaign, Brock’s operation became an indispensable part of Clinton’s machinery — just as in the old days, leading the attacks against her enemies.

This time, though, he helped Clinton push the boundaries of finance rules by coordinating their efforts.

Soon after Clinton entered the race, Brock announced that Correct the Record, a super PAC he created in 2013, would work directly with her campaign. That wouldn’t break campaign finance rules prohibiting coordination with a candidate, group representatives argued, because no money would be spent on ads; Correct the Record would instead concentrate on posting material for free. With that, the organization assumed key roles for Clinton, handling opposition research and the “rapid response” job of blasting out fiery attacks on her critics.

Campaign leaders came to rely on Brock, particularly for the dirty work.

When Clinton’s aides were upset about a quote in another negative book about her, they discussed how to fight back: “I’m sure Brock and team would love to go at him,” wrote Christina Reynolds, then Clinton’s director of rapid response.

Brock boasted in an interview about pulling off maneuvers others still considered taboo, such as heeding the campaign’s orders to quickly “saturate the airwaves” last week to spin the revelation that the FBI is looking at the emails of a Clinton aide.

“That is the kind of thing we couldn’t have done before,” Brock said, pointing to federal rules that other super PACs still interpret to ban such conversations with a presidential campaign. “This legal interpretation is breaking new ground.”

Donors have taken notice. A Brock fundraiser alerted Podesta late last year that billionaire hedge fund manager James Simons was intrigued that Correct the Record was “a coordinated PAC,” as he mulled giving as much as $1 million. Simons did not write the mega-check, but one of his closest associates from his Renaissance Technologies hedge fund, Henry Laufer, gave half a million dollars, the group’s biggest contribution.

Campaign finance reformers were appalled.

“Hugely problematic” and illegal is how Brendan Fischer, associate counsel for the Campaign Legal Center, described the arrangement Brock has brokered with Clinton’s campaign. The group has filed a complaint with the Federal Election Commission.

“A billionaire can’t come in and say, ‘I’m going to pick up the salary of the campaign manager.’” Fischer said. “If Clinton had kept her opposition research team in-house, a donor couldn’t have said, ‘I’m going to pay for all the salaries of the researchers.’”

Even Clinton’s allies worried that the unprecedented setup has gone too far, the hacked emails show. “This does seem shady,” Clinton friend Neera Tanden wrote to Podesta. His response was brief: “Brock $ machine!”

“That’s fine,” Tanden wrote back. “But skirting if not violating law doesn’t help her.”

The campaign declined to comment on the emails hacked from Podesta; it has not confirmed their authenticity.

Brock, 53, with owlish glasses and a shock of white hair, made his name trying to discredit Anita Hill’s sexual harassment allegations about Supreme Court Justice Clarence Thomas, and publishing Arkansas state troopers’ allegations about Bill Clinton’s womanizing.

But as Clinton’s impeachment loomed, Brock refashioned himself as a devout defender of the Clintons, providing insider intelligence for their defense. He brought his story to the fundraising circuit, impressing many in Clinton’s circle of wealthy donors with his experience in the inner workings of the right. They gave generously.

Brock built a network of 10 nonprofits and political groups, all sharing an office in downtown Washington. They include Correct the Record, the $9.4-million super PAC; and Media Matters for America, devoted to pushing back against the right-wing media. Brock earns about $575,000 per year.

In the same suite of offices is the small firm belonging to Brock’s friend and fundraiser, Mary Pat Bonner, which collects a 12.5% commission on money brought in. The arrangement could net Bonner’s company about $4 million this cycle, positioning her for earnings that dwarf those of chief fundraisers at much bigger and more sophisticated operations. Bonner did not respond to requests for comment and Brock could not say how much she earns.

“Mary Pat’s take-home pay is her own business, not mine,” Brock said. He praised her ability to find new donors and keep old ones happy and argued that other groups spend even more on fundraising. “I don’t think I would have been able to do it any other way,” he said.

The Brock operation is also providing for the care and feeding of a select group of longtime Clinton warriors. Sidney Blumenthal, the former journalist and advisor in the Bill Clinton White House, earns $200,000 a year providing “strategic advice” — a payment made public only by mistake. Also earning $200,000 for the same type of gig, said Brock, is James Carville, the fervent surrogate who helped run Bill Clinton’s 1992 campaign.

The financing agreements are a source of tension among Democrats. Brock and Bonner alleged a conspiracy against them by fellow Democrats when news reports about Bonner’s impressive salary emerged just before Clinton entered the race. It moved Brock to briefly quit the board of Clinton’s biggest super PAC.

“Welcome to whacko land,” Podesta wrote in an email about the dust-up to Tina Flournoy, Bill Clinton’s chief of staff.

When a panicked Bonner pleaded with Podesta for advice on how to respond to the “press nightmare” the spat had become, Podesta curtly warned her that obsessing would only garner more media attention. “Stop feeding the beast,” he wrote.

Bonner regularly pestered Podesta to mollify big donors. When a senior Clinton policy advisor declined to offer a job to the granddaughter of Qualcomm co-founder Irwin Jacobs, Bonner pushed Podesta to intervene. The woman was later hired.

It was not the only time Brock created heartburn at Clinton’s Brooklyn headquarters, where staffers might be able to turn to Brock for help but had no reins to pull him in.

Podesta became enraged during the Democratic primaries when he learned Brock was making an issue out of the health record of Vermont Sen. Bernie Sanders. As Podesta fumed, Tanden hypothesized that the idea to demand Sanders’ medical records might have been hatched by Bill Clinton, reflecting what she suggested is the former president’s penchant for political skulduggery.

Podesta and Tanden, who runs the liberal Center for American Progress, pondered whether Brock could be a GOP plant, a real-life “Manchurian candidate,” or just an “unhinged narcissist.” Tanden, who called Brock a “nut bar” and a “menace” in the emails, asserted that the Clintons’ continued confidence in Brock reflected their own taste for conspiracy theories and dirty-tricks politics.

Brock laughed it off, saying he had been called worse in campaigns. He says Podesta has enthusiastically helped build and nourish his network since 2003, and a few snarky emails do not reflect their relationship. He interprets Podesta’s “money machine” note as a nod to his fundraising prowess, not an insult.

As for Tanden, Brock said she sent an apologetic note, explaining that she was trying for “dark humor.”

“I told her I totally understood and I was sorry her privacy had been violated,” Brock said. “As far as I’m concerned, we’re all on the same team.”

Brock said angst inside the campaign about the legality of his role dissipated long ago, after Clinton’s own attorneys explained what he calls his “novel” arrangement that found a way around rules that prohibit campaigns from working directly with super PACs.

Clinton’s campaign, Brock said, would have severed ties with Correct the Record if it were doing anything risky. “If they had doubts about the legal nature of our work, they wouldn’t touch us with a 10-foot pole,” he said.

Brock doesn’t anticipate the partnership ending on election day, though he has no interest in joining the government payroll as a White House advisor. He says lawyers are looking at how Correct the Record could function as part of a Clinton presidency, battling new investigations already threatened by Republicans.

“There will be plenty of work to do,” Brock predicted.

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Twitter: @evanhalper, @jtanfani

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