Now let's just say that, for some reason - however politically unlikely - the Senate DOES vote to remove him. What implications would this letter have, as to the President's intended course of action at that point? Sounds like he would refuse to step down.
When Clinton was impeached, he obviously strongly disagreed that the charges merited his removal. But I don't believe he ever challenged the constitutional right of Congress to impeach and remove him, if they voted too.
I'm sure the President is displeased, but this kind of language verges on the unconstitutional. One wishes his advisors would offer him better counsel, and insist that they can't be part of dangerous rants like this.
The President has every right to argue his case, and possibly prevail. But he does not have the right to subvert and denigrate Congress' constitutional powers.
