Penn -- who served as a pollster and adviser to former President Bill Clinton and a chief political strategist for Hillary Clinton’s 2008 presidential campaign -- said "this process must now be stopped, preferably before a vote in the Senate."
The blistering column follows new revelations about an FBI informant who reportedly had discussions with multiple Trump campaign members in 2016.
Former deputy FBI Director Andrew McCabe testified last year that no Foreign Intelligence Surveillance Act (FISA) warrant would have been sought against another Trump adviser without the Steele dossier information, according to a GOP House Intelligence Committee memo released in February.
Deputy Attorney General Rod Rosenstein issued a statement noting that "if anyone did infiltrate or surveil participants in a presidential campaign for inappropriate purposes, we need to know about it and take appropriate action."
Rosenstein is a fact witness, and Mueller is a friend of Comey, disqualifying them both,” Penn wrote, adding later that Sessions “needs to take back his Justice Department.”