The idea that the President's powers aren't limited by Congress is a radical--and dangerous--trendFew parts of our Constitution generate more mythology than Article Two, which creates the office of the President.
The Constitution grants the president the following exclusive powers: (1) he is commander in chief of the armed forces; (2) he can require "heads of departments" to give him their opinions in writing; (3) he receives ambassadors, and; (4) he grants pardons for federal offenses. In addition, he shares with the Senate the treaty power and the appointment authority ("advise and consent"), and can make "recess appointments" if Congress is not in session. He can veto a bill, subject to override by 2/3 of both Houses. He can convene Congress on "extraordinary occasions," but ordinarily may not force it to adjourn. He is required to send a state of the union message "from time to time," and he shall "take care that the laws be faithfully executed."
It's not an overwhelming list. But on this vague framework, executive theorists have constructed a view of the office that is sometimes little short of dictatorship. That constitutional myth affects presidents of both parties and their supporters.
Consider that, in the days after 9/11, Congress authorized President Bush to "use all necessary and appropriate force against those nations, organizations, or persons he determines planned, authorized, committed, or aided the terrorist the terrorist attacks that occurred on September 11, 2001, or harbored such organizations or persons, in order to prevent any future acts of international terrorism against the United States by such nations, organizations or persons." That may be the broadest such resolution ever passed.