Sessions fiasco

Attorney General Sessions' departure is very clearly a firing by Trump.  The law requires that in case of a firing that the next official in line becomes acting Attorney General until the Senate confirms a replacement.

The next person in line is Rod Rosenstein.  He should become Acting Attorney General, not this Whittaker guy, however capable he may be.  Congress must assert itself and invalidate Trump's action as a clear abuse of power.

Is this more blundering by Trump, ignorant of most rules and norms, or is a a blatant act on a par (or worst than) Nixon firing of Cox?  Either way, the Congress and courts, if necessary, must act quickly to reset the balance.

Will Mitch McConnell fail us yet again?