Regardless of any of these factors you say he faced how could he have ever got Senators or Congressman to resign, quit, or cause to fire? After all these same people where elected as well and it's not like the President no matter how vast his powers maybe he was never going to be able to get rid of them. That in fact would kind of go against the whole separation of powers thing. That is actually up to the American People and who they chose to elect or not elect.
When he said "drain the swamp" I always took that to mean the unelected bureaucrats and others that have way too much power and are way too corrupt. Others may have taken it differently.