Bush administration seeks to downplay report due for release next week.
The bill means that congress has so far approved $650bn to be spent on the Iraq war since it began more than five years ago.
Another almost $200bn has been spent on operations in Afghanistan so far, congressional officials say.
“Our nation has no greater responsibility than to support our men in women in uniform – especially because we’re at war,” Bush said.
College benefits for troops and veterans will be doubled as part of the new funding package.
It also provides for a 13-week extension of unemployment benefits and $2.7bn in emergency flood relief for the US Midwest.