It is important at this point that Congress offer specific constructive approaches to what's proven to be a foreign policy disaster because we've got too much at stake to simply stand on the sidelines and criticize... If we simply cut off funding without any structure for how a redeployment takes place, then you could genuinely have a Constitutional crisis or at least a crisis on the ground where the president continues to send troops there but now they're being shortchanged in terms of armaments and support... The notion that as a consequence of that [2002 Congressional] authorization, the president can continue down a failed path without any constraints from Congress whatsoever is wrong and is not warranted by our Constitution.

Interview on Iraq with the Associated Press (30 January 2007)

Obama wants troops home by spring '08 - politics - Decision '08 - Barack Obama News | NBC News[nbcnews.com]