You presume the whole of Congress cares enough about its own role to actually do something. If the whole of Congress did care enough then it would mean that a significant number of democrats are willing to take the necessary action. The best to hope for is that the Republicans do so well in November that the (D)oddering fool can do nothing but acquiesce to wiser heads.
My other hope would be that a bipartisan group would go to him quietly and convince him of his errors but he'd have to get rid of Klain first who is probably more of a problem than we realize.