That's another pitfall in the "AUMF authorizes this" argument. Quite a few Republican Senators have expressed the same sort of "misgiving." Another way this argument is phrased is that "If the President is going to 'misconstrue' or 'extend' Congressional acts, you can bet we'll be circumspect about granting him any authority."
Maybe they will be more careful then, in the future, when writing AUMFs....
so this should go on THEM, not Bush, IMHO.
BUT, it still isn't a political winner...because I think that people with common sense would assume that this kind of surveillance would be part of ANY WAR PLAN.
Congress doesn't "grant" the president authority, the Constitution does. Congress doesn't have the power to change anything in the Constitution.