Vince Cable said the leaking of an internal party poll to the Guardian by Lord Oakeshott was "totally inexcusable and unacceptable".
The poll suggested the Liberal Democrat leader would lose his seat in 2015.
Mr Cable said:
Lord Oakeshott's actions are totally inexcusable and unacceptable. I have made it very clear repeatedly that he does not speak or act for me.
Commissioning and publishing polls without the consent of the Member of Parliament, as in the case of Sheffield Hallam, is utterly reprehensible.
There are undoubtedly raw feelings in the wake of poor local and European election results. We need to respond in a measured way. Public speculation about the leadership is an unwelcome distraction and as I made absolutely clear yesterday there is no leadership issue as far as I'm concerned.