A New York hedge fund heiress who co-owns a boutique cookie bakery has emerged as one of the most influential figures behind Donald Trump’s presidential campaign, and arguably the conservative movement as a whole.

Leaning on the fortune amassed by her father, Rebekah Mercer has steered her family’s rapid rise over the course of just a few years from the conservative fringe to the white-hot center of the most dramatic election season in years. And no matter the results on Nov. 8, the Mercers are positioned to reshape the American right for years to come in their anti-establishment image.

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But the family’s rise, facilitated by an increasingly aggressive network of Mercer-backed institutions and operatives, has prompted worry within the GOP about an attempted takeover, and questions from across the political spectrum about what the Mercers intend to do with the influence they’ve purchased.

Efforts to deduce the family’s intentions have focused largely on the family patriarch, Robert Mercer, 70, a pioneer in quantitative trading. But Bob Mercer, as he’s known, is mostly only writing multimillion-dollar checks that fund the family’s political operation; it is his daughter, Rebekah Mercer, 42, who is running the operation, according to more than 15 personal and political associates of the family.

It is Rebekah Mercer, according to these sources, whose frustration with what she saw as the political ineffectiveness of the Koch brothers’ network led her to redirect Mercer money to build a rival operation.

It is Rebekah Mercer who directs a family foundation that, according to tax returns, has more than doubled its giving between 2011 and 2014, donating $34.6 million to 30 conservative nonprofits over which she holds varying degrees of sway — from the Government Accountability Institute, which produced "Clinton Cash," a book that damaged Trump’s Democratic rival Hillary Clinton, to the venerable Heritage Foundation, where she sits on the board.

It is the same Rebekah Mercer who urges campaigns and clients who want her father’s funding to hire a data firm owned largely by the family called Cambridge Analytica, which now counts Trump’s campaign among its clients.

And it is Rebekah Mercer whose meeting with Ivanka Trump and her husband, Jared Kushner, reportedly set the stage for the Mercers to switch their support to Donald Trump after the family’s first choice, Ted Cruz, dropped out of the race, rather than retreating to the sidelines as so many other big donors did.

Rebekah Mercer now sits at the nexus of Trump’s universe. So influential has she become that her conversation with Trump during an August fundraiser in the Hamptons has been widely credited with spurring the rookie candidate to shake up his campaign team by turning its leadership over to two of her closest confidants.

Pollster Kellyanne Conway, who has worked with Mercer on a pro-Cruz super PAC, became campaign manager, while the new job of campaign CEO went to Steve Bannon, a campaign novice who helped run both the Government Accountability Institute — which has received at least $2 million from the Mercer foundation — and Breitbart News, the intensely pro-Trump nationalist website in which the Mercers have invested. This month, Trump rounded out his newly reconfigured campaign leadership by bringing in yet another operative with whom Mercer has worked — David Bossie, who previously ran both an anti-Clinton super PAC that received $2 million from Bob Mercer in July and an anti-Clinton nonprofit called Citizens United that received $3.6 million from the Mercers’ foundation from 2012 through 2014.

Rebekah Mercer did not respond to requests for comment. Conway, Bannon and Bossie either declined to comment or did not respond to requests for comment. And most conservative insiders approached for this story were loath to speak on the record for fear it might jeopardize their chances of receiving funding from Mercer's intensely private family. Mercer, some said, has scolded allies for calling attention to her — even when it’s been positive.

But granted anonymity, the professional and personal associates offer one overarching explanation for the Mercers’ otherwise eclectic series of political moves: Bob and Rebekah Mercer harbor a deep and abiding enmity toward the political establishment.

That context helps account for a surge in political investments that might otherwise come across as quixotic, wasteful or ideologically inconsistent. It explains their shift from Cruz (a socially conservative constitutionalist with a hawkish streak who benefited from $13.5 million from Mercer super PAC spending) to Trump (whose commitment to social and national security conservatism is uncertain but who has nonetheless benefited from $2 million from Bob Mercer and counting), as well as their support for failed long-shot congressional candidates such as Kelli Ward and Arthur Robinson.

“They see the establishment as a very real threat to freedom in America, and they see the need to defeat it,” said Brent Bozell, president of the Media Research Center.

An operative who has worked with the Mercers said their enmity is especially pronounced toward the GOP establishment. “They want to blow things up and start from scratch,” said the operative, pointing to Breitbart News’ fawning coverage of the unsuccessful long-shot challenger to House Speaker Paul Ryan in last month’s GOP primary in Wisconsin.

In all, a POLITICO analysis found that the Mercers have made $73.5 million in disclosed politically oriented donations since the Supreme Court’s January 2010 Citizens United decision paved the way for unlimited political spending through super PACs and other nonprofits. Of that, $39 million came in donations to political candidates and committees from members of the family, and $34.6 million came from the family foundation to conservative nonprofits.

That tally doesn’t come close to approaching the combined spending of the Koch network, which expects to spend $750 million in the run-up to the 2016 election. But the Mercers’ spending does put them in league with donors like fellow New York hedge fund tycoon Paul Singer and members of the Ricketts family, who have become gravitational centers in conservative politics. And that’s even before considering the Mercers’ investments in Breitbart News and Cambridge Analytica, for-profit companies that don’t disclose investors but that could have a greater long-term impact on conservative politics than any given campaign or nonprofit group.

A conservative who travels in the same social circle as Rebekah Mercer described her motivations thusly: “This is about political power. This is about who controls the data and the narrative, and who ultimately is going to end up calling the shots.”

But Bozell, a longtime fixture of the GOP’s right flank who is widely seen as having been among the first to cultivate the Mercers as political donors about a decade ago, said he would advise them against trying to take over the conservative movement.

“They have become great sources of support, obviously, for the conservative movement,” said Bozell, whose Media Research Center has received more than $10 million from the Mercers' foundation and included Rebekah Mercer on its board until at least 2014, according to tax documents filed by the MRC and the Mercers' foundation. “But control? No.”

Bozell declined to discuss the family’s plans or Rebekah Mercer’s role in its political activism.

“I do know that she is brilliant,” he said. “She is thoughtful and she has got a keen analytical mind, which came right from her father, and my guess is that her father is very comfortable with her involvement, whatever that may be.”

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Rebekah Mercer, who is known to friends as “Bekah,” is the middle of three daughters born to Bob and Diana Mercer and raised in suburban Westchester County, New York.

Described almost universally as intelligent and hard-working, Mercer graduated from Stanford in 1996 with a dual degree in biology and mathematics, then received a master’s in operations research from Stanford. She went to work on Wall Street as a trader, before retiring to raise the four children she had with her husband, Sylvain Mirochnikoff, a managing director at Morgan Stanley.

Associates describe the family as close-knit and culturally conservative but also known to spend lavishly on their wide-ranging hobbies.

Bob Mercer has commissioned a $2.7-million model train set and multiple massive yachts, including one with décor inspired by Alice in Wonderland and Peter Pan.

In 2006, Bekah Mercer and her sisters bought and took over the popular bakery Ruby et Violette in the Hell’s Kitchen neighborhood of midtown Manhattan. The bakery later shuttered its storefront and now sells exclusively from a website that invites customers to “seduce someone” with its sweets. Bekah Mercer still features her ownership and management of the company prominently in her bios on the websites of the various Mercer-backed nonprofit groups on whose boards she sits.

While the three Mercer sisters worked together on the bakery, they had different interests outside of it.

The youngest daughter, Heather Sue Mercer, is a competitive poker player, like her father. Conservative operatives buzz about the family’s annual holiday parties at their Long Island estate, which feature blackjack and poker tables. The Mercers supply chips — free of charge — that can be redeemed at the end of the night for lavish prizes such as gold Rolexes, according to people who have attended.

The oldest daughter, Jennifer, or "Jenji," Mercer shares her mother’s interest in horses. Bob Mercer built a lavish riding center in Florida and invested in a Colorado horse park and an international equestrian center in North Carolina featuring five arenas and 500 stables.

Bekah Mercer, associates say, is the member of the family who most shares Bob Mercer’s passion for politics.

Bob Mercer “supports each of his daughters' efforts in their own individual areas of interest,” said a Republican strategist who has spent time with the family.

While Bob Mercer is known as quiet and difficult to engage, he “lights up when he’s with Rebekah and just becomes really alive,” said a donor who has spent time with the pair at political events.

The pair shifted their political engagement into high gear in 2010 after a few years of being significant — but not elite — players in conservative finance circles. That was the year that Bob Mercer became co-CEO of Renaissance Technologies, one of the world’s most successful hedge funds.

The 2010 election cycle was the first after the Supreme Court’s Citizens United decision created a Wild West campaign-finance landscape. And Bob Mercer jumped right in, pouring $640,000 into a super PAC — one of the first — that funded attacks against Oregon Democratic Rep. Peter DeFazio, who had sponsored legislation that would have raised taxes on hedge funds. DeFazio nonetheless handily defeated his Republican challenger, Arthur Robinson, whose Oregon Institute of Science and Medicine, which stockpiles human urine for medical research and attacks the scientific consensus on climate change, has been the recipient of Mercer funding. (Robinson’s unsuccessful 2012 and 2014 challenges to DeFazio were also boosted by Mercer-funded attacks on DeFazio.)

In 2010, Bekah Mercer also joined the board of the Media Research Center, and, under her direction, the family’s foundation began escalating its grant writing. In 2011, it increased its donations to $7 million. Within three years, that figure was $18 million.

In 2011, Bob Mercer reportedly invested $10 million in Breitbart, and around 2013, as first reported by POLITICO, the family became the largest investor in Cambridge Analytica, the American spinoff of the British data analysis firm Strategic Communications Laboratories Group, or SCL. Bannon played a role in brokering that deal, according to two operatives familiar with it, and the company’s officials, with help from Bekah Mercer, began presenting Cambridge Analytica’s product as superior to both a Koch-backed data firm and that of an RNC-blessed data outfit.

It was around 2011 that the Mercers joined the network of donors spearheaded by the billionaire industrialists Charles and David Koch, according to four operatives familiar with the family’s involvement in the network.

These sources said Bob and Bekah Mercer started attending the twice-a-year donor summits, convened by the Koch brothers, at which the brothers raised tens of millions of dollars for a Koch-controlled political and public policy network. Comprised of advocacy groups that don’t disclose their donors, as well as i360 and a super PAC called Freedom Partners Action Fund, the Koch network has in some ways, in terms of influence, rivaled the RNC. The Mercers began giving at least $1 million a year — and much more in some years — to the network, according to the operatives familiar with the family’s involvement.

At a summit in 2013 or 2014, Koch operatives bought a shipment of cookies from Ruby et Violette as welcome presents, which were left in donors’ rooms with notes thanking Bekah Mercer, according to two of the operatives familiar with the family’s involvement in the network. The move was seen a deft bit of donor maintenance intended to build good will with the Mercers, who, as the Koch operatives were aware, were branching out on their own even as they kept a foot in Koch world.

But by the beginning of the 2014 cycle, Bob Mercer was signaling that his middle daughter was taking charge of the family’s political portfolio, according to operatives who work with the family. They said it had become clear that Bekah Mercer strongly preferred investing in campaigns and causes over which she could exert control.

Bekah Mercer had grown increasingly frustrated with the Kochs’ approach. It is not as politically aggressive as she preferred and also much more supportive of trade and immigration, said operatives and donors familiar with the Mercers’ involvement with the Kochs. They said Bekah Mercer also questioned the effectiveness of the spending orchestrated by the Kochs’ operatives and bristled at what she perceived as their unwillingness to heed her advice.

Bekah and Bob Mercer stopped attending the Koch donor summits and dialed back their giving to the network, according to the operatives familiar with the family’s involvement in the network.

“Some people believe only they can achieve whatever goal it is, and I think she is in that camp,” said one Koch network donor who worked with Bekah Mercer. “And she wasn't totally aligned with us. She's much more populist.”

According to a Republican who advises her, Bekah Mercer has grown wary working with other political activists and operatives, in general. “She’s a very serious person. Very smart. Very dedicated to what she’s doing, and I think she feels that a lot of these people are taking advantage of her,” said the adviser. “She wants to have an impact, and she hasn’t found people she can trust.”

Indeed, while Bob Mercer finished 2014 as the sixth biggest donor of the cycle, with $8.4 million in disclosed donations, perhaps more significantly, by the end of the cycle, the Mercers were perceived within conservative politics as their own center of gravity, unmoored from — and in competition with — other major donors-backed networks and even the RNC, which Breitbart railed against.

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Heading into the spring of 2015, Ted Cruz’s presidential campaign appeared to be the perfect proving ground for the Mercers' fully operational political machine.

The Mercers had grown enamored with the Texan after meeting him at a gathering of the fiscal conservative outfit Club for Growth, to which Bob and Bekah Mercer have donated $2.3 million over the years.

For Bekah Mercer, even the Club, a leading supporter of many fiery Republican insurgents, sometimes proved too cozy with the establishment. After Joe Scarborough spoke at the group's annual donor retreat in Palm Beach, Florida, in early 2013, Mercer stood up and confronted the MSNBC host, who had recently called Cruz a "carnival barker" on air. She told Scarborough she did not know who had invited him and pointed out that the Club was a big backer of the Texas senator, according to a person who was present. Scarborough did not respond to a request for comment.

Breitbart News was cranking out a stream of favorable Cruz stories, and both the Mercer-backed pro-Cruz super PAC, Keep the Promise I, and the Cruz campaign signed up Cambridge Analytica. And only hours after the Texas senator officially launched his campaign at the Christian university Liberty University, he and his wife appeared at Bekah Mercer’s extravagant Upper West Side apartment for a fundraiser.

But things started getting testy almost immediately. At the fundraiser, Bekah Mercer fumed about campaign manager Jeff Roe, who had chewed out Cambridge’s technicians for missing deadlines in building the campaign’s website, according to a person present at the fundraiser.

Mercer and Bannon continued to clash with Cruz aides, including Roe and campaign chairman Chad Sweet, in a series of conference calls about Cambridge’s performance and its billing practices, according to two people with knowledge of the conversations. Mercer was “infuriated” by a campaign official’s contention that rather than providing some secret sauce, Cambridge Analytica was merely using information that was publicly available, according to the people.

It didn’t take long for Mercer’s dissatisfaction with Cruz’s team to extend beyond the dispute over Cambridge. “She was down on the whole campaign,” said one Cruz adviser. “She thought the Iowa operation was terrible. She clashed repeatedly with Jeff Roe. She was very down on the ground game. She thought early on that [Wisconsin Gov. Scott] Walker was eating our lunch.” Mercer also expressed her frustration that the campaign did not hire Iowa operative Chuck Laudner, a veteran of Rick Santorum’s successful caucus campaign, who instead went to work for Trump.

After each primary debate, aides to Cruz — a champion debater as an undergrad at Princeton — braced for Mercer’s withering critiques of his performance.

“Bekah kind of wore out her welcome on the campaign,” said one of the operatives who has worked with Mercer.

Mercer also clashed with mega-donor Toby Neugebauer, an energy investor, over control of the constellation of four pro-Cruz super PACs with variations of the Keep the Promise name, and tried to install controversial evangelical activist David Barton to help run them.

By January, Breitbart had soured on Cruz as well, and its coverage increasingly tilted toward Trump, at Cruz’s expense. Neither Sweet nor Cruz himself were able to persuade Mercer to intervene with Bannon. Instead, she and Conway told Cruz and his team that Breitbart was independent and there was nothing they could do to shape the coverage, according to two people familiar with the interactions.

After Cruz lost the South Carolina primary in February, the campaign stopped using Cambridge Analytica’s models, though it continued to work with its team of embedded data scientists, who had PhDs in the hard sciences and were viewed favorably at Cruz headquarters in Houston. For two weeks in April, as Cruz fought for his political life, Cambridge Analytica executives ordered the employees it had embedded at Cruz campaign headquarters to walk off the job over a contractual dispute, though some continued their work for the campaign in secret from home.

Cruz spokeswoman Catherine Frazier disputed that Mercer expressed any discontent at the fundraiser and said: "Our campaign had a productive and positive relationship with Cambridge Analytica, and they performed important work for the campaign. Rebekah is a friend and we are thankful for her support during our campaign. She loves this country and she is willing to stand and fight for freedom."

As the Cruz campaign succumbed to Trump, Republican mega-donors like Singer, the Ricketts family and the Kochs remained mostly on the sidelines, reluctant to make major investments in their party’s incendiary presumptive nominee. In that vacuum, Bekah Mercer set about building bridges to Trump’s campaign. The Mercers converted their pro-Cruz PAC into an anti-Clinton one, and Conway prepared to pass the reins to Bossie, who had worked with the Mercers on a conservative film-production venture.

“Rebekah’s a loyal Republican and is always going to support the nominee,” said a personal friend of the Mercer family, who maintained that Trump had been her second choice from the start.

But even as the Mercers lined up with Trump, the GOP nominee’s then-campaign chairman, Paul Manafort, seemed to be trying to keep them at arm’s length. “They had done everything they could to push themselves into Trump world and then had gotten pushed back out by Manafort,” said a Republican operative familiar with the situation.

Manafort had long questioned the effectiveness and costs of Cambridge Analytica, which had pitched the Trump campaign last year, to no avail. And when Mercer and Bossie urged that Conway be hired as Trump’s pollster, Manafort in mid-May hired his longtime associate Tony Fabrizio.

But ever-persistent, Mercer would prevail. In June, she met with Ivanka Trump at Trump Tower. Days later, Conway joined the campaign.

Then, in mid-August, as the campaign was buffeted by a storm of controversy surrounding Manafort’s ties to pro-Kremlin factions in Ukraine, Mercer met with Trump at the Hamptons fundraiser and recommended a leadership change. Soon after that, the campaign announced the hiring of Bannon as the campaign’s CEO and Conway’s elevation to campaign manager. And two days later, the campaign asked for and received Manafort’s resignation.

Most of the Mercer associates interviewed for this story predict that their influence won’t end with the Trump campaign.

“I don’t think it’s about Trump. Trump is just a vehicle,” said one operative who’s worked with Bekah and Bob Mercer. “It’s about wanting to be a player and wanting to beat Hillary, in that order. Because if you remember, they wanted to use Cruz as a vehicle before that. They do want to beat Hillary, but they also want to beat the Kochs and Paul Singer and the Ricketts,” said the operative, referring to other conservative mega-donors.

But how that influence manifests itself after 2016 is uncertain. Firebrand Iowa Rep. Steve King, who has received campaign donations from the Mercers and gotten to know them a bit through the conservative event circuit, suggested that Bekah Mercer's views are a driving force in the activism she and her father engage in.

“They wouldn’t be the pair they are if it weren’t for Rebekah’s passionate commitment to the conservative cause,” said King, who — like the Mercers — supported Cruz’s presidential campaign in the primary, before throwing his support to Trump in the general.