The transfer, announced during a lunch hosted by Sen. Steve Daines (R-MT), the chairman of the National Republican Senatorial Committee, is the largest in the organization’s history. Thune also set the previous record, $2 million, in 2016.

Daines convened the meeting to give an update on where key Senate races stand less than two months out from Election Day. But the lunch, held at NRSC headquarters in Washington, D.C., quickly became another flash point over the leader race.

Sen. Rick Scott (R-FL), another Republican vying to replace McConnell, announced a max-out leadership PAC check of $300,000 during the meeting. 

A spokesperson for the third candidate, Sen. John Cornyn (R-TX), has not disclosed whether he made a transfer, but Cornyn has for years been one of the most prolific fundraisers among Senate Republicans.

In total, the NRSC raised more than $6.5 million at the lunch on Tuesday, according to a source familiar with the matter. Daines had cited a $10 million transfer Vice President Kamala Harris made to the Democratic Senatorial Campaign Committee last week as the impetus for Tuesday’s “cattle call.”

“If there’s one thing that Kamala Harris can do well, maybe the only thing, it’s raise money. So we’ve got a gap that we need to close,” Daines told the Washington Examiner ahead of the lunch.

“We’ve got winnable races as we’ve expanded this map,” he added. “Our biggest challenge right now is getting the resources out to the front lines to win.”

Fundraising is foundational to the job of GOP leader, with Thune and Cornyn in particular attempting to demonstrate they can fill the shoes of McConnell, who will step down from leadership at the end of the year. Thune has raised $26 million this cycle, according to a source familiar with his fundraising.

Meanwhile, Cornyn has raised $23 million through June, the end of the second quarter. He has yet to disclose his fundraising into September.

Raising money is not the only metric by which McConnell’s successor will be judged. Cornyn, who served as GOP whip until term-limited out of the job in 2019, sent a letter to his colleagues Monday outlining his priorities were he to become leader.

He named extending the 2017 tax cuts that will expire next year and preserving the legislative filibuster among them.

Still, Cornyn and Thune have tried to outdo each other on the fundraising front. Each spent the August recess attending events for the Republicans running in battleground Senate races as special guests.

In a new wrinkle, the two have also tried to signal their support for former President Donald Trump by attending Trump campaign fundraisers.

The fundraising is meant to build rapport with the Republicans who could join them in the Senate next year, each of whom will get a vote on the next leader. Trump is also expected to weigh in on the race.

But for now, nearly the entire GOP conference remains publicly undecided. Just two Republicans have endorsed in the leader race: Sens. Mike Rounds (R-SD) and Markwayne Mullin (R-OK), each of whom is supporting Thune.

A lot will depend on the outcome of the November election. Even Daines has been floated as a “dark horse” candidate should Republicans perform particularly well.

Republicans have a favorable map and are all but guaranteed a new seat in West Virginia. But Harris has injected new life at the top of the Democratic ticket and could buoy incumbents in a slate of battleground states.

The seat that could decide the majority, in Montana, is considered a “toss-up” by some political handicappers and “leans Republicans,” according to others.