Liberal Democrat deputy leader Simon Hughes, who was the party's president until the end of 2008, denied that he ever knew about the allegations against Lord Rennard.
Mr Hughes told ITV News: "I can be categoric, I knew nothing of any allegation made to me over the four years when Lord Rennard was the chief executive. Nothing came to me formally, nothing came to me informally.
"I didn't see inappropriate behaviour and I was not aware of any complaints floating around and I think if they had been made in any specific way, they would have come my way."
Mr Hughes added it was "clear at the time" that Lord Rennard's 2009 resignation from his post as chief executive was down to health reasons.