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The FBI visited Senate Republican Leader Mitch McConnell's campaign headquarters Wednesday, Fox News has learned, after the senator claimed his office was bugged.

McConnell aides first made the allegation Tuesday, bringing in the FBI after a recording of a private strategy meeting on potential opponent Ashley Judd was published Tuesday in a liberal publication.

The FBI visited the Louisville office for an hour Wednesday as part of an "ongoing criminal investigation," Fox News was told.

The campaign handed over "pertinent information," though it's unclear what that information entailed.

McConnell and other Republicans have accused liberal foes of using "Watergate"-style tactics to record the meeting, though nobody has come forward to say how the meeting was taped.

Several snippets of the audio from the February strategy sessions were published Tuesday by Mother Jones magazine, along with a lengthy article. The recording, obtained from an unnamed source, included McConnell aides discussing ways to politically damage actress Ashley Judd, who at the time was talked about as a possible McConnell challenger. The aides suggested going after her mental health and views on religion.

McConnell campaign manager Jesse Benton said Tuesday that the senator's office is "working with the FBI" on the issue and has notified the U.S. attorney in Louisville at the FBI's request.

The campaign, on Twitter, later accused opponents of "illegally wiretapping" the office.

Sen. Jerry Moran, R-Kan., chairman of the National Republican Senatorial Committee, also urged liberal and Democratic groups to denounce the tactics.

"Secret recordings, private conversations leaked, reports of bugs -- these Watergate-era tactics have no place in our campaigns," he said.

But the Democratic Senatorial Campaign Committee said late Tuesday that McConnell is playing "the victim."

"The DSCC doesn't know if this tape came from a disgruntled Senate staffer who was forced to dig up dirt on their boss' potential opponents or another source, but its content is a clear example of how Mitch McConnell is the living, breathing embodiment of everything that is wrong with Washington," the DSCC said. "It is beneath the office of Minority Leader to engage in this kind of trivial politics. He should apologize to the millions of Americans who suffer from depression and don't believe it's a laughing matter."

The FBI declined to comment.

Judd had been seriously considering a challenge to the Senate Republican leader in Kentucky until she opted against running last month. The McConnell team meeting covered in the Mother Jones article reportedly took place on Feb. 2.

The advisers could be heard discussing possible avenues of attack against Judd, one of which concerned her mental state.

"She's clearly, this sounds extreme, but she is emotionally unbalanced. I mean it's been documented. Jesse can go in chapter and verse from her autobiography about, you know, she's suffered some suicidal tendencies. She was hospitalized for 42 days when she had a mental breakdown in the '90s," one strategist said.

One aide also said Judd is "critical ... of traditional Christianity."

"She sort of views it as sort of a vestige of patriarchy," the aide continued. "She says Christianity gives a God like a man, presented and discussed exclusively with male imagery, which legitimizes and seals male power, the intention to dominate even if that intention is nowhere visible."

The meeting was evidently a preliminary session to toss around ideas. The campaign ultimately never had to deploy any of them, as Judd decided not to run.

Fox News' Chad Pergram contributed to this report.