Congress has the sole power to declare war. However, the president is the commander in chief. Any law requiring him to "consult" would make him less than the commander in chief and would therefore be unconstitutional.
I know the big brains in Washington don't actually care about the Constitution but once in a while couldn't they just pretend?
Only Congress can declare war, but the President has the power, as Commander in Chief, to undertake hostilities any time he considers it necessary. That is the President’s Constitutional power.