BREAKING: Trump tweets that Mick Mulvaney will be acting chief of staff 

Mueller controversy: Trump has repeatedly broken his oath of office. Now it's up to Congress to hold him accountable.

Matthew Whitaker’s appointment as the new acting attorney general has renewed concerns that President Trump might intervene in the special counsel’s Russia investigation. But if the president can’t be trusted to protect the oath of office, that job now falls to Congress, says Corey Brettschneider, the author of “The Oath and the Office: A Guide to the Constitution for Future Presidents.”