Re-read your Constitution. In a declaration of belligerency, it does not require Congress to use the precise words: "Declaration of War".
Both the Iraq War Resolution and the Authorization For The Use of Military Force (War on Terror) are declarations of war in their effect -- whether you personally agree with them or not.
It is a hopeless open-ended, perpetual, and subjective concept (something the founders disdained) which puts absxolutely no check no the president. As I said, Obama may well consider you a "terrorist" for even visiting this site.
Again, why do you put such trust in Obama to decide such details.