Robert S. Mueller III, the special counsel, is said to be in talks about interviewing current and former senior officials, including Reince Priebus, the recently ousted chief of staff.
He has made it clear that his mission is to dismantle the E.P.A.’s environmental mission. His critics say he is deploying extraordinary secrecy as he does so.
The White House aide spoke at the annual gathering of the National Association of Black Journalists for a panel that was moderated by Ed Gordon, a host at Bounce TV.
The president lashed out at the Senate leader over health bill failures, perhaps the most potent evidence yet that he is willing to train fire on allies.