One Time Congress Tried to Prevent a President From Firing Someone, It Ended in Impeachment
"...'The bill to protect Mueller would not place an outright ban on presidential firing of an executive branch employee, and thus is constitutional,' said Curt Levey, president of the Committee for Justice, a conservative legal group.
'I really don’t see a parallel between this bill and the  tenure of office law, because it doesn’t stop Trump from firing Mueller, who is an executive branch employee,' Levey told The Daily Signal. “If it did, it would be unconstitutional. Congress can set up a path for appeals...'"
Read the full article in The Daily Signal.