Nick Clegg has admitted his party made "very serious mistakes" in its handling of sexual harassment claims against its then chief executive Lord Rennard.
The Deputy Prime Minister continued to insist that he was personally unaware of any specific allegations by women in the party until they were broadcast last week.
But he said the issue was "in the background" when the peer - who strongly denies the claims - retired from his senior role on grounds of ill-health in 2009.
"There were some very serious mistakes and the women were not listened to and were let down," Mr Clegg said as he was questioned on the controversy during his weekly phone-in on LBC 97.3 radio.
"I so much believe that it is crucial that you treat people with respect and dignity in everything you do - and that is what I expect of people in the organisation I lead. That, clearly, did not happen here, to put it mildly."
Mr Clegg said an email sent to a senior aide by the Daily Telegraph shortly before the 2010 election setting out detailed allegations "was not passed on to me".
"He felt that four days before the general election, because he knew what the answer was - that I didn't know anything about the allegations - and he would just send an answer back to the Daily Telegraph.
"Clearly something went seriously wrong in the organisation as a whole that people were not talking to each other."
He also insisted that a face-to-face conversation with then MP Sandra Gidley after he became leader in 2007 had been "of a general nature".
"She raised it in general terms. She wasn't aware of any specific allegations and, as she has confirmed today, I didn't either," he said.
The programme's final caller - called Herbie - asked Mr Clegg: "How in God’s name do you expect (people in Eastleigh) to vote for you with this scandal going on and uneasiness?"
Mr Clegg answered by outlining the party’s record in the area, where voters will pick Chris Huhne's replacement on Thursday.
When pressed on details of what was said during various discussions, the party leader said he could not be expected to remember what was said in conversations six years ago.
"All I can tell you is the truth as I recollect it now," he added.
Lord Rennard issued a fresh denial of any wrongdoing this week and has said he is ready "co-operate with any properly-constituted inquiry".