Army Powers Vested in the U.S. Congress
In deference to these powerful precedents, the Founding Fathers vested in the United States Congress the self-same powers to raise an army, raise taxes, and most importantly TO WAGE WAR, giving only George Washington's modest styling Commander in Chief, to the U. S. President, subject to Congressional oversight.
Furthermore, the Founding Fathers recognized the dangers of an unfettered rogue mutinous dog President — the awful spectacle of Oliver Cromwell then being in their eyes, confirmed somewhat later by the even worse excesses of Napolean Bonaparte — by giving to the U. S. Congress the authority to impeach and remove from office the Self-Anointed Chief Deciders grasping authority run amok.
So, yes! The Congress has a great deal of Constitutional authority vested in itself, vastly more than simple powers of oversight. And if George W. Bush doesn't come soon to heel, the scholars of arcane Constitutional law will soon begin appearing from the woodwork, as they did in the weeks before Nixon resigned.