Remember - if the Senate version of the resolution is DIFFERENT from the House's, then the House will have to approve a conference committee report, which means that House members will have to be in DC for a vote and not back home campaigning.
In reality, though, this is all just grandstanding for the purpose of enhancing their stature within the left wing of the party. A chance to bash Bush without real meaningful consequence and to curry favor within the cocktail A-list party ranks of the media. This has NOTHING to do with the debate and EVERYTHING to do with SHOW.
Michael