The Iraq supplemental spending bill to be voted on Thursday by the House Appropriations Committee lacks enforcement language that some of Congress’s most liberal members wanted to see.

Members of the Progressive and Out of Iraq caucuses have said that their support for the bill is likely to rest on the strength of such language.

The bill says that troops must be withdrawn as early as October if President Bush cannot certify that Iraq has made progress in disarming militias and sharing oil money and that the U.S. and Iraqi forces are "making substantial progress" in reducing sectarian violence.

But the language simply orders that troops be deployed in that instance. According to a partial copy of the bill provided to The Hill, the legislation fails to stipulate that "funds may not be obligated" -- language backed by some liberal members of the lower chamber.

Out of Iraq Caucus members hold 12 seats on the Appropriations Committee. Since Democrats have only a four-vote margin on the panel, unified opposition by the caucus would sink the bill if Republicans also vote against it.