The White house has admitted it edited and altered the transcripts. The Congress may or may not have what you call oversight of the doj, but they can subpoena and question them, and of course they have power over their funding. Navarro and Bannon ended up in jail for ignoring subpoenas. The thing is if you think of Congress and the doj as adversaries you really need to rethink that. You have no champion in Washington and there is no cavalry coming to save you. No one wants any more cans of worms opened in this year or any other year. Trump is a designated common enemy of the power structure, and he gets no immunity from persecution.