A U.S. Senate race in Georgia has turned into a proxy war ensnaring three national Republican committees and top GOP congressional leaders in a battle over whose allies get to work for which candidates.

The fight pitted the political lieutenants of Senate Majority Leader Mitch McConnell (R-Ky.) against top political advisers to House Minority Leader Kevin McCarthy (R-Calif.) and Republican National Committee Chairwoman Ronna McDaniel.

Ostensibly, the fight concerned McConnell’s explicit support for Sen. Kelly Loeffler (R-Ga.), who was appointed to fill the vacancy left when Johnny Isakson (R) resigned in early January due to health problems. McConnell’s team has tried to suffocate any Republican opposition to Loeffler, part of his long-standing policy to blacklist any political firms that work for candidates challenging a GOP incumbent.

But this came against the backdrop of President Trump’s impeachment. Trump’s family and close allies pushed Georgia Gov. Brian Kemp to appoint Rep. Douglas A. Collins to replace Isakson because, in his role as ranking Republican on the House Judiciary Committee, Collins emerged as a fierce defender of the president.

Instead, Kemp appointed Loeffler as the state’s first female U.S. senator, tapping a political novice with a family fortune and willingness to burn at least $20 million to win the special election. Three weeks after Loeffler was sworn in, Collins jumped into the race anyway.

What has ensued since is the type of internecine battle that left many Republicans stunned over its intensity.

It also illustrates the different rules that these national party committees employ in doling out the hundreds of millions of dollars they control during election years, with leaders like McConnell and McCarthy exerting an outsize ability to dry up consulting revenue if they deem certain firms disloyal.

After years of producing hamstrung nominees from contested primaries, the National Republican Senatorial Committee announced in 2013 that it would not allow any dollars to go toward firms that worked for GOP challengers to incumbents. Only one GOP incumbent has lost a primary challenge since then.

The Democratic Senatorial Campaign Committee has no such rule, so consultants for Rep. Joe Kennedy (D-Mass.) face no blowback in his challenge to Sen. Edward J. Markey (D-Mass.).

McConnell’s team offers no apology for its tactics. Its blacklist policy is well-known to every Republican consulting firm, as is its well-honed image of being willing to be the toughest kid in the political sandbox.

“With this emotional, ill-informed decision, Doug Collins has united conservatives in opposition to his candidacy, and Senator Loeffler has quickly assembled more Republican support in Georgia than Collins ever knew existed,” said NRSC spokesman Jesse Hunt, calling the four-term congressman “a swamp creature.”

McConnell does not want to risk a divided GOP field in the initial Nov. 3 ballot, which under special election rules would force the top two finishers into an unpredictable Jan. 5 runoff if no candidate clears a 50 percent majority. He wants Loeffler to win on the first ballot in the jungle primary rather than Democrats pushing one candidate toward an outright victory while the Republican vote splits. The Democratic Senatorial Campaign Committee and former gubernatorial candidate Stacey Abrams are united behind the candidacy of the Rev. Raphael Warnock, pastor of the Atlanta church where the Rev. Martin Luther King Jr. once preached.

Collins, a familiar face on Fox News, is repositioning himself as the anti-establishment outsider because Loeffler is tied so closely to McConnell.

“Kelly Loeffler and her allies have spent over $8 million on ads and haven’t moved the needle. Georgia voters know that Doug is the president’s foremost defender. They are just not buying Loeffler,” said Dan McLagan, Collins’s campaign spokesman, dubbing it the “Potomac panic polka.”

Soon after Isakson announced his retirement plans in August, Collins began considering the Senate race. In early October, his campaign paid almost $30,000 to John McLaughlin, a well-known Republican pollster. With impeachment looming, Collins signed Convergence Media onto his House campaign account to boost his online fundraising presence.

Rob Simms and Mike Shields founded the firm after a wealth of experience helping run the National Republican Congressional Committee and the RNC. They maintain a close connection to McCarthy, whose campaign paid Convergence more than $1 million for fundraising consulting in 2019, according to Federal Election Commission records. The firm receives a $15,000-a-month retainer from the NRCC and is poised to work on the committee’s vast “independent expenditures” unit that does advertising in individual House races.

The firm plays a smaller role in Senate races, collecting almost $1.5 million in 2018 from the NRSC for work on three Senate races.

Kevin McLaughlin, NRSC’s executive director, served as the blunt-force object in taking on those considering working for Collins, according to participants who spoke on the condition of anonymity to discuss the internal fight.

McLaughlin, a longtime member of “Team Mitch,” as the political operation bills itself, delivered a forceful recitation of the committee’s policy, explaining how firms would lose access to consulting contracts.

Clients of the firms considering the Collins’s race heard from NRSC officials.

One GOP consultant told McLaughlin that he was not afraid of the purported $20 million Loeffler was willing to spend. “$100 million,” McLaughlin responded.

The message was clear: Loeffler, a business executive and co-owner of a WNBA team, is willing to spend whatever it takes to win. Her husband, Jeffrey Sprecher, is chairman of the New York Stock Exchange.

The three GOP leaders — McConnell, McCarthy and McDaniel — never spoke to one another about the feud, according to their advisers. But the messages were sent at the highest staff levels.

NRSC officials complained to top advisers of McDaniel, who employs Shields’s wife, Katie Walsh, as a consultant. And McConnell’s world made their displeasure clear to McCarthy’s orbit.

The harder McConnell’s team fought, the deeper some firms dug in on their support of Collins.

Trump’s lack of clarity on the Senate race has probably played a critical role in the final decisions.

At a White House celebration after his impeachment acquittal, Trump further confused things by praising Loeffler and Collins. “Something is going to happen,” the president said, suggesting everything would work out.

Loeffler’s side saw that as Trump looking to appoint Collins to something to get him out of the race. Collins’s team read it as exactly the opposite: Trump looking to get Loeffler out.

It became impossible for firms like Convergence to go with Collins if it were possible Trump would endorse Loeffler somewhere down the line.

In a roughly 10-day span after Collins entered the race, Convergence Media declined to work on his Senate race, followed by a direct-mail firm and John McLaughlin, the GOP pollster.

The Collins campaign is stocking its lineup with other firms and vowing to fight, happy to run as the aggrieved outsider.

“The same D.C. establishment political swamp,” Collins tweeted Friday, “that tried to stop President Trump is trying to stop me now!”