Hyperion
Banned
Trouble is that the Speaker and Ppt are not necessarily of the same party as the President, so that a double vacancy could in effect reverse the verdict of the last election. At least a Sec of State is generally of the same party as the President who appointed him.
However, I suppose the 25A has gone a long way to make the problem moot.
Presidents have crossed the party line before in appointing or keeping a person in a Cabinet position, ie Obama keeping Robett Gates as Secretary of Defense. Depends on the POTUS, depends on the job he's looking to have filled.