It would be unconstitutional for the president to initiate hostilities with Iran without congressional approval. It would also be folly for us Americans to leave such a decision to a group that has blundered so badly in making such decisions in the past.
Here is a further explication of this two-fold position.
THE CONSTITUTIONAL ARGUMENT
The powers of the commander-in-chief may extend to dealing militarily with urgent matters, where the national interest requires immediate action and cannot await congressional deliberation and approval. But the present issue with Iran is no such matter.
The question whether to go to war to prevent some country from developing nuclear weapons is a long-term, fully premeditated decision. And the Constitution gives the power to make that decision to the Congress.
This approach avoids the necessity for the Democrats to say anything about national security that the Bushite propagandists can use in their usual way: support the president or you'll die. And the Bushites are so adamant about the president as dictator --apparently so constitutionally (as it were) incapable of acknowledging the legitimate rights and powers of the other branches of government-- that there's a good possibility that the entire battle with the regime can be fought on these constitutional grounds.
Not only does focusing on the constitutional issue have the great advantage of avoiding those national security grounds that apparently are so frightening for the Democrats to confront the Bushites on, it also provides grounds that are both advantageous to the Democrats and vital for the country.
In other words, the Bushite beating of the drums of war against Iran provides an important opportunity to dramatize the larger issue --I would say the largest issue facing America-- of the president's lawlessness, and of the vital importance of re-establishing such vital American principles as the system of checks and balances, the three co-equal branches of government, and the rule of law.
And if the Republicans refuse to support a resolution along these lines, affirming Congress's constitutional authority of declaring war, this provides yet another opportunity. Such a refusal would enable the Democrats to raise to prominence yet another issue: Did not you Republicans take an oath to protect and defend the Constitution? How can you justify putting your loyalty to your partisan president ahead of your sworn oath to defend the Constitution?
In other words, Republican support for Bush's usurpations on this issue can be an opening through which the Republicans can be hammered for the larger pattern of their being accessories to the Bushite assault on the Constitution they swore upon the Bible that they would defend.
And then there’s the practical question: would you want to buy another war from the people who manufactured the debacle in which we're now mired in Iraq?
If the possibility of war must be faced, why would we want for it to be made by those who, in Iraq, made so many serious misjudgments?