The National Republican Senatorial Committee is taking an unusually aggressive posture toward one of its conservative antagonists, putting out word that GOP groups shouldn't hire a consulting firm that works with the Senate Conservatives Fund.

The New York Times's Jonathan Martin reports:

Even more striking, a senior official at the committee called individual Republican Senate campaigns and other party organizations this week and urged them not to hire the firm, Jamestown Associates, in an effort to punish them for working for the Senate Conservatives Fund, a group founded by Jim DeMint, then a South Carolina senator, that is trying to unseat Senator Mitch McConnell of Kentucky, the Republican leader, and some other incumbents up for reelection next year whom it finds insufficiently conservative.

“We’re not going to do business with people who profit off of attacking Republicans,” said Brad Dayspring, a spokesman for the committee. “Purity for profit is a disease that threatens the Republican Party.”

The committee has conveyed the same message, privately, to 2014 Senate candidates such as Representatives Steve Daines of Montana and Tom Cotton of Arkansas, the Republican National Committee, the National Republican Congressional Committee (the senatorial committee’s House counterpart), the Republican Governors Association and Mike DuHaime, the chief strategist for Gov. Chris Christie of New Jersey, for whom Jamestown also does work.

The move is the latest iteration in a long-running battle of wills between the NRSC and conservative groups. After these groups helped more conservatives candidates defeat a number of establishment-friendly candidates in recent years, the committee opted for a more hands-off approach — believing that fighting against these groups only helped them raise money and put wind in the sails of their anti-establishment message.

The Senate Conservatives Fund has carved an increasingly prominent role in GOP primaries and GOP politics more broadly. It has vocally suggested that Senate Minority Leader Mitch McConnell (Ky.) should step aside and has endorsed his primary challenger, businessman Matt Bevin.

SCF head Matt Hoskins said the move is all about McConnell being scared.

“This is happening because Mitch McConnell is having a complete meltdown,” Hoskins said. “He can’t defend his record so he’s threatening and attacking everyone who disagrees with him."

Jamestown, a well-known and respected GOP firm, declined to comment to Post Politics.

Rep. Mark Sanford (R-S.C.) tweeted a note of support for the firm, noting that it was with him when GOP leaders deserted his special election campaign this year.

Update 5:12 p.m.: Sen. Ted Cruz's (R-Tex.) state director, John Drogin, tweets the following: