This is an appropriations bill, which means that Bush can unquestionably veto it, just as Clinton threatened to veto the funding bill for his Kosovo war. That one was a little different, in that the Republican House at one point doubled what he asked for, directing the extra funding into other areas of the military that they felt were neglected (little or no domestic pork, unlike some of what we have seen recently.)
On the other hand, there are plenty of quotations that indicate that Republicans in those days -- even those like Sen. Jesse Helms who had voted against and still opposed the War Powers Act of 1973 -- seemed to have little doubt about Congress's legitimate role in determining the scope and length of a military action.
Again, Kosovo was different in that there was no conceivable case to be made for American security, whereas the Iraq war has been pitched as part of a response to the events of September 11th -- correctly or incorrectly.
A question is whether a President could veto a new Iraq resolution that did not involve appropriations, but rather was explicitly an act of Congress exercising its constitutional power to "declare war" by "undeclaring war."
On first blush, it wouldn't seem that the President could veto such a binding resolution, but this would probably be an aspect of Constitutional law without any comparable Supreme Court precedent, since all declarations of war and authorizations for war have come at the request of a President, and all withdrawals from military action have involved at least the acquiescence of the President.
The President could argue that the "promote the emergence of a democratic government to replace that regime" part of the original Iraq resolution hasn't been completed. We will leave aside the point that this portion of the bill should never have existed -- candidate Bush in the 2000 campaign, who rightly criticized the Clinton/Gore administration for "nation-building" and for a lack of humility on the world stage, would have agreed. Too bad he started listening to the wrong advisers -- and it his responsibility to listen to the right people.
The crafting of a binding resolution would force the House and the Senate to come to agreement on what the country's military objectives in the Middle East should be. The Framers came to the conclusion that the Congress as a whole should have the power to declare war (Alexander Hamilton's proposal was to give the Senate with that sole power, upon which the executive was to have "the intire direction of War when authorized or begun."
What was eventually settled on was wise, since Congress is the best reflection of the will of the populace as a whole. Silence in the Constitution on the exact ways in which the executive and legislative branches are to share the powers and responsibilities of war was also probably wise. As we have reviewed some very interesting historical comments, especially regarding Congressional opposition to the Mexican-American War and WWI, we have been hard-pressed to find the specific mechanisms by which revered figures like Daniel Webster and Henry Clay believed that Congress could exercise its power to stop a war.
Political consensus renders moot the need to make clear things about which the Constitution appears to be deliberately vague. This would mean, of course, that Sen. Lieberman plus at least 9 Republican Senators and a majority of "Blue Dog" Democrats would have to sign on to the resolution -- and ideally, such a resolution would gain far broader Republican support and even the acquiescence of the President. Given the unpopularity of the war at present, one doubts that any resolution passed today by Congress would read in a way that would please the most fervent supporters of the war -- but neither would it please its most fervent opponents. For both groups it's all or nothing.
The question is whether the Democrats in Washington have the courage to undertake the crafting of a new binding resolution that could actually pass. They will get more political points from a tough, "get out of Iraq now" funding bill that the President can veto, followed by their giving him (as Obama proposes) the funding he wants -- i.e. enough rope for Bush to hang his own party.
That is probably what Congressional Democrats will do -- but it flies in the face of what Democrats currently say they want (and with which many of us on the right strongly agree) -- a clear reassertion of Congressional power when it comes to declaring war such as the Constitution indicates. And by extension, Congress would be reassuming the sometimes unpleasant and politically inconvenient responsibilities that come with those powers.
Either way, we should hope that this isn't pushed into the federal courts, since war is fundamentally a political issue that needs to be worked out between Congress and the President. In other words, worked out by "we, the people."