The Senate Conservatives Fund's latest target is the GOP's leader in the Senate. 

The conservative group has launched a radio ad in Senate Minority Leader Mitch McConnellAddison (Mitch) Mitchell McConnellMcConnell expects Paul to return to Senate next week Former Hill staff calls for mandatory harassment training Gaming the odds of any GOP tax bill getting signed into law MORE's (R-Ky.) district that scolds him for not supporting an effort that risks a government shutdown over funding ObamaCare.

ADVERTISEMENT
"Republicans in Congress can stop ObamaCare by refusing to fund it, but Sen. Mitch McConnell refuses to lead the fight," a narrator says in the ad.

According to The Associated Press, the ad highlights McConnell's reluctance to sign a letter in which he'd pledge his support to vote against any government funding bill that includes money for ObamaCare. 

It also alludes to McConnell campaign manager Jesse Benton's comments — from a private conversation that leaked — in which Benton said he was "holding my nose" to work with McConnell. 

"The ObamaCare bill stinks, and holding your nose won't make it any better," the narrator says.

The radio ad is backed by $50,000 and will launch Tuesday.

McConnell is facing a Tea Party challenge from Kentucky businessman Matt Bevin, and the polarizing issue of defunding ObamaCare — popular with the conservative grassroots — could become a difficult issue for him.

His campaign spokeswoman, Allison Moore, asserted in an email that it was "absurd" to suggest McConnell hadn't fought against the law.

"There is nobody in Congress who has done more to fight Obamacare since day one than Mitch McConnell and any assertion to the contrary is absurd," she said. 

Moore also suggested that McConnell is working to "unite conservatives."

"Senator McConnell is a co-sponsor of the repeal bill, a co-sponsor of the defund bill, and has said that if elected Majority Leader getting rid of Obamacare would be the first thing on his agenda.  Senator McConnell's primary goal is to unite conservatives rather than exacerbate differences to stop this train-wreck of a law and give us the best chance for success," she said.

The Senate Conservatives Fund hasn't endorsed Bevin, but its continued attacks on McConnell are an indication they're moving closer to supporting his opponent.

The group has targeted six other GOP senators who, like McConnell, have not signed the defunding ObamaCare letter: Sens. Richard BurrRichard Mauze BurrJuan Williams: The shame of Trump's enablers Five takeaways from the social media hearings Overnight Tech: Senators demand tech firms do more on Russian meddling | House Intel releases Russian-promoted ads | Apple CEO says 'fake news' bigger threat than ads | Ex-Yahoo CEO, Equifax execs to testify on breaches MORE (N.C.), Lindsey GrahamLindsey Olin GrahamCNN to air sexual harassment Town Hall featuring Gretchen Carlson, Anita Hill Trump wrestles with handling American enemy combatants Flake: Trump's call for DOJ to probe Democrats 'not normal' MORE (S.C.), Lamar AlexanderAndrew (Lamar) Lamar AlexanderObamaCare becomes political weapon for Democrats Senate passes resolution requiring mandatory sexual harassment training Sen. Warren sold out the DNC MORE (Tenn.), Johnny IsaksonJohn (Johnny) Hardy IsaksonCongress is working to honor America’s heroes Bipartisan lawmakers can rebuild trust by passing infusion therapy bill 24 senators co-sponsor bipartisan ObamaCare deal MORE (Ga.), Jeff FlakeJeffrey (Jeff) Lane FlakeGOP rushes to cut ties to Moore Flake on Moore defenders: 'This cannot be who we are' GOP senators raise concerns over tax plan MORE (Ariz.) and Thad CochranWilliam (Thad) Thad CochranWhite House requests B for missile defense to counter North Korea Senate narrowly passes 2018 budget, paving way for tax reform Live coverage: The Senate's 2018 budget 'vote-a-rama' MORE (Miss.).

Many Republicans oppose the strategy of threatening to shut down the government over defunding ObamaCare, arguing the GOP will take a political hit if voters are upset by the shutdown.

--This piece was updated at 1:14 p.m. to reflect comment from McConnell's campaign.