Lib Dem president Simon Hughes has privately assured Charles Kennedy he is not planning a leadership bid.
Kennedy's leadership is under the microscope
Mr Hughes met Mr Kennedy on Wednesday morning to deny rumours he has his eye on the top job, the Guardian reports.
Mr Hughes, who was defeated by Mr Kennedy in the 1999 leadership contest, has given similar assurances on two previous occasions, it has emerged.
The most recent was shortly after the general election, Mr Hughes told BBC Radio 5 Live.
He said he had been forced to act because rumours were circulating that he was "organising" for a leadership bid.
Mr Hughes told Five Live: "A colleague accused me of something which I was very angry about, so I went personally to Charles Kennedy and said, 'Someone is making allegations about me which are not true'."
"If he was to decide to stand down of his own accord that is a different question - that is open and I have told him that."
He said he hoped Mr Kennedy was "relieved and grateful and reassured" by his words.
Mr Hughes stood against Mr Kennedy six years ago in the battle to succeed former leader Paddy Ashdown.
"He beat me. I came in second place and I gave him a personal assurance that I would never stand against him," Mr Hughes told the BBC.
Mr Kennedy, who is in Blackpool for the Lib Dems' annual conference, has been forced to defend his "consensual" leadership style after criticism he was more a chairman than a party leader.
In an interview with Guardian Unlimited, Mr Hughes said he had assured Mr Kennedy for a third time on Wednesday morning that he would not stand.
"Because this has become such an exciting issue amongst journalists, we had a third conversation this morning, where, for the sake of the record, I said to him again, in front of witnesses, "Charles, just in case anyone asks, I'm saying to you again whilst you're the leader, I stood against you to get the job and you won and I lost so, whilst you're the leader, there is no challenge from me" so therefore we've had more conversations.
"It's no big deal. We're a party that when you elect someone you let them get on with the job and they choose when to go.
"Charles has indicated he's going on and that's the nature of this party."
Following May's general election, Mr Kennedy was re-elected unopposed as Lib Dem leader, with a mandate stretching beyond the next general election.
Earlier Paul Holmes, chairman of the parliamentary Liberal Democrat Party, insisted there was "no leadership challenge" and Mr Kennedy had "strong support" among MPs.
"If Charles stood down when he has fought three general elections, I think Simon would be a contender for the leadership ," added Mr Holmes, who backed Mr Hughes' leadership bid in 1999.