President's Power from What War Declaration?

Bush continues to claim powers consistent with the commander-in-chief in war time. Now insisting it is both necessary and legal to order eavesdropping on U.S. citizens without involving the courts because "we are at war".
Since he is framing this in a legal context, I would first like to know what Congressional declaration vests him with this power and, second, just whom that declaration was against.

I have not heard that these are Iraqi "terrorists" he is investigating without oversight from either the Judicial or Legislative branches. If he isn't referring to the resolution authorizing him to disarm Saddam Hussein in support of U.N. resolutions, I am unaware of any legally declared war in progress, and I think we need to seriously question the legality of Bush's action.

King George? Indeed.