The Congressional vote was not close:
House of Representatives 296 for, 133 against and 3 non voting
Senate: 77 for versus 23 against.

Authorization for Use of Military Force Against Iraq Resolution of 2002 (Engrossed as Agreed to or Passed by House)
HJ 114 EH
107th CONGRESS
2d Session
H. J. RES. 114

JOINT RESOLUTION
To authorize the use of United States Armed Forces against Iraq.
Whereas in 1990 in response to Iraq's war of aggression against and illegal occupation of Kuwait, the United States forged a coalition of nations to liberate Kuwait and its people in order to defend the national security of the United States and enforce United Nations Security Council resolutions relating to Iraq;

Whereas after the liberation of Kuwait in 1991, Iraq entered into a United Nations sponsored cease-fire agreement pursuant to which Iraq unequivocally agreed, among other things, to eliminate its nuclear, biological, and chemical weapons programs and the means to deliver and develop them, and to end its support for international terrorism;