Jonny Oates, who was the Lib Dems' director of electoral communications at the time, received email questions from the Daily Telegraph about the peer's alleged conduct. He issued a denial of the claims in April 2010.
Mr Oates, who is now the Deputy Prime Minister's chief of staff, said yesterday that it was "untrue" Mr Clegg had been made aware of the claims.
Mr Oates told the Daily Mail: "No, I did not speak to Nick about it. I didn’t need to. I was aware of the general concerns about Chris Rennard and I knew that the whole problem in dealing with it was we didn’t have specific allegations. There was no way I could really ascertain facts.
He added: "I felt we couldn’t take it any further. We were in the middle of the general election, Nick would have been on the road. Chris had resigned as chief executive of the party, he wasn’t acting for us at the time, so no, I didn’t discuss it with Nick.
"Whether I should have done, this review panel can look at that I’m sure. In hindsight probably I should."
Lord Rennard denies the allegations against him.