The most senior Republican in the US Senate presided over a meeting of his top staff at which they discussed how to attack the actor Ashley Judd, a potential challenger to his seat, as suicidal and emotionally unbalanced, it was claimed on Tuesday.

Mother Jones magazine published a secret recording of an opposition research meeting between Mitch McConnell and his senior aides that took place on 2 February, at a time when Judd was thought to be preparing the groundwork for a run against the powerful Kentuckysenator.

Judd decided not to run – citing the need to spend time with her family – but for much of the past six months there had been intense speculation that she would seek to enter politics.

Some conservative groups had already shot attack ads taking aim at her Hollywood career that painted her as an out-of-touch elitist liberal.

Mother Jones's tape reveals that McConnell was at a meeting where Judd was discussed in brutal terms. "I assume most of you have played the, the game Whac-A-Mole? This is the Whac-A-Mole period of the campaign … when anybody sticks their head up, do them out," McConnell says at the start of the 12-minute tape.

A male voice then acts as the presenter of a series of tactics and revelations to be used against Judd, saying that her background was a "haystack of needles" for anyone seeking to attack her. The group discussed Judd's history of interviews and statements in which she has praised gay marriage, criticised sexism within Christianity, and revealed her ties to areas outside Kentucky, such as her houses in Scotland and Tennessee.

The presenter then says: "This sounds extreme, but she is emotionally unbalanced. I mean it's been documented ... you know, she's suffered some suicidal tendencies. She was hospitalized for 42 days when she had a mental breakdown in the 90s."

In a statement, McConnell's campaign manager Jesse Benton attacked the recording of a confidential meeting. "We've always said the Left will stop at nothing to attack Sen. McConnell, but Nixonian tactics to bug campaign headquarters is above and beyond," he said.

Benton said that McConnell's office had notified the Federal Bureau of Investigation to ask for a probe to see if the recording had been a criminal act. "Obviously a recording device of some kind was placed in Senator McConnell's campaign office without consent. By whom and how that was accomplished will presumably be the subject of a criminal investigation," he said.

Judd has spoken previously about her traumatic childhood and suffering from depression. In 2006 she told a magazine that she had spent 47 days in a Texas facility being treated for "codependence in my relationships; depression; blaming, raging, numbing, denying and minimizing my feelings."

Last month Judd spoke in Washington DC and opened up about her own experiences as a "a three-time survivor of rape". She told a crowd at George Washington University: "I have no shame, because it was never my shame to begin with – it was the perpetrator's shame."

Judd had pulled out of contention for the Kentucky race at the end of March, following news that she was splitting from her husband, Scottish race car driver Dario Franchitti. "I have spoken to so many Kentuckians over these last few months who expressed their desire for a fighter for the people and new leader," she said in a statement at the time.

"While that won't be me at this time, I will continue to work as as hard as I can to ensure the needs of Kentucky families are met by returning this Senate seat to whom it rightfully belongs: the people their needs, dreams and great potential."

As well as the pre-emptive attack ads by Republicans, reports had also emerged that some senior Democrats were concerned that Judd's celebrity status would make it hard for her to beat the otherwise potentially vulnerable McConnell. In February Jimmy Cauley, a long-time Kentucky Democratic strategist, told Roll Call a Judd run would be "a catastrophe" for other Democrats in the state, who faced being dragged down with her if she lost.