What Do You Call Eight Fired U.S. Attorneys at the Bottom of the Ocean?
Here's the deal. There's no doubt that U.S. Attorneys, like all other political appointees, serve to pleasure the President. That means, among other things, that he can hire them (subject to appropriate confirmation) and fire them at will.
However, if a U.S. Attorney is fired in order to stop an investigation that the administration doesn't like, that is called obstruction of justice. This would certainly qualify as a high crime or misdemeanor.
The Senate is responsible for making this determination, and if there is any evidence of this crime it should be allowed to do so.