Sen. Mitch McConnellAddison (Mitch) Mitchell McConnellCongress had a good couple of weeks — now let's keep it going McCarthy: 'The Mueller investigation has got to stop' McConnell: Mueller 'ought to wrap it up' MORE (R-Ky.) is taking fire from the Senate Conservatives Fund (SCF), which has endorsed his primary challenger Matt Bevin, for his support for a Kentucky judge who recently ruled the state must recognize same-sex marriages.

McConnell recommended U.S. District Judge John Heyburn to the federal bench in the early 1990s and, in testimony on his behalf, referred to him as a “progressive Republican” and an "excellent judicial appointment.” Heyburn ruled last month that Kentucky must recognize same-sex marriages performed in other states.

In a new minutelong radio ad, the SCF highlights McConnell’s testimony on Heyburn’s behalf and charges that the senator recommended him because of “political cronyism.” The ad will run statewide for a week beginning on Tuesday and is backed by just under $30,000.

“Mitch McConnell called Heyburn an ‘excellent judicial appointment’ and praised him for being ‘progressive,’ ” a woman says in the ad.

A man responds: “ 'Progressive’ means liberal. Now, why would McConnell recommend a liberal?”

“Political cronyism. Heyburn donated money to McConnell and served as a county chairman for his campaign,” the woman replies.

The man goes on to declare McConnell “should admit right now that recommending Judge Heyburn was a mistake.”

“Yeah. First it was funding ObamaCare, then it was giving Obama a blank check to raise the debt ceiling, now it’s liberal judges,” the woman replies. “I’m voting for conservative Matt Bevin instead.”

Gay marriage has become a bit of a flashpoint in the race following Heyburn’s ruling, and Bevin has knocked McConnell for his support of the judge before.

McConnell has said he opposed the court’s decision on the issue.

“I am a traditionalist and support that position, but regardless of one’s personal view on the issue, we should be able to agree that only the people of Kentucky, through the legislative process, should have the authority to change the law, not the courts,” he told the Courier Journal, shortly after Heyburn issued his ruling.

McConnell spokeswoman Allison Moore called the ad "absurd and pathetic."

"This is the kind of ad voters expect to hear from people who are days away from boxing up their personal effects and auctioning off the remaining printer cartridges in the office. It is so absurd and pathetic that they ought to stop troubling radio listeners with the obligation of switching stations and admit they have no justification to attack Senator McConnell," she said in an email to The Hill.

McConnell is favored in his primary and is expected to face a tough contest from Democratic state Secretary of State Alison Lundergan Grimes in the general election.

— This piece was updated at 9:30 a.m. to reflect comment from McConnell's campaign.