The basis for the argument is the founding fathers whose foreign policy was one of not interfering in the internal affairs of other nations and a policy of going to war only when we are directly threatened - and even then only after CONGRESS has specifiically declared war.

Now, before you get into this Giuliani emotionalism about 9/11, keep in mind that 9/11 would never have happened if the United States government had not been interfering in the internal affairs of Middle Eastern countries since the 1950s, and keep in mind that Iraq had nothing to do with 9/11. What should have happened in this case was that CONGRESS should have made a formal declaration of war (as required in the Constitution) against Al Qaeda and the Taliban government of Afghanistan and we should have fought that war until we either killed or captured all of their leaders (including Osama bin Laden). As a reminder, here's what the Constitution says about Congress' role in the conduct of warfare:

To declare War, grant Letters of Marque and Reprisal, and make Rules concerning Captures on Land and Water;

To raise and support Armies, but no Appropriation of Money to that Use shall be for a longer Term than two Years;

To provide and maintain a Navy;

To make Rules for the Government and Regulation of the land and naval Forces;

To provide for calling forth the Militia to execute the Laws of the Union, suppress Insurrections and repel Invasions;

To provide for organizing, arming, and disciplining the Militia, and for governing such Part of them as may be employed in the Service of the United States, reserving to the States respectively, the Appointment of the Officers, and the Authority of training the Militia according to the discipline prescribed by Congress.

Now, here's what it says about the President:

The President shall be Commander in Chief of the Army and Navy of the United States, and of the Militia of the several States, when called into the actual Service of the United States.