There's a supreme law of the land in the US. 

It's called the US Constitution

Section. 8.

Clause 1: The Congress shall have Power To lay and collect Taxes, Duties, Imposts and Excises, to pay the Debts and provide for the common Defense and general Welfare of the United States; but all Duties, Imposts and Excises shall be uniform throughout the United States;

Clause 10: To define and punish Piracies and Felonies committed on the high Seas, and Offences against the Law of Nations;

Clause 11: To declare War, grant Letters of Marque and Reprisal, and make Rules concerning Captures on Land and Water;

Clause 12: To raise and support Armies, but no Appropriation of Money to that Use shall be for a longer Term than two Years;

Clause 13: To provide and maintain a Navy;

Clause 14: To make Rules for the Government and Regulation of the land and naval Forces;

Clause 15: To provide for calling forth the Militia to execute the Laws of the Union, suppress Insurrections and repel Invasions;

Clause 16: 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;

Clause 17: To exercise exclusive Legislation in all Cases whatsoever, over such District (not exceeding ten Miles square) as may, by Cession of particular States, and the Acceptance of Congress, become the Seat of the Government of the United States, and to exercise like Authority over all Places purchased by the Consent of the Legislature of the State in which the Same shall be, for the Erection of Forts, Magazines, Arsenals, dock-Yards, and other needful Buildings;--And

Clause 18: To make all Laws which shall be necessary and proper for carrying into Execution the foregoing Powers, and all other Powers vested by this Constitution in the Government of the United States, or in any Department or Officer thereof.

There's no such thing as a Democratic, not Republican war mentioned in that Constitution.  There's no such thing, no such power granted in that document to the President of the US to wage war.

Wars are declared by Congress. 

CONGRESS:  To define and punish Piracies and Felonies committed on the high Seas, and Offences against the Law of Nations;

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

Like it or not, that is the supreme law of the land.

THE PRESIDENT:  Clause 8: Before he enter on the Execution of his Office, he shall take the following Oath or Affirmation:--"I do solemnly swear (or affirm) that I will faithfully execute the Office of President of the United States, and will to the best of my Ability, preserve, protect and defend the Constitution of the United States."

 That is what the US Constitution says about the war in Iraq.  It's what the US Constitution says about this president of the US.

That is what the US Constitution says about who conducts wars and punishes pirates, et al.

That is what the US Constitution says about whether this president is fulfilling his oath of office.