Then again, if congress does refuse, or he anticipates this and doesn't bother seeking authorization, and attacks anyway (which Cheney would likely prefer as it would just validate--in his mind--his theory of plenary executive power), what will congress do then? Again, I'm not so sure.

And unless and until congress makes its intentions clear by voting to defund the war, the admininstration will likely view this as an implicit green light to attack Iran. Or, perhaps, a yellow light, i.e. "We don't want you to attack, but we're not going to stop you or do anything about it if you do".

The threat of an attack on Iran may well be a political ploy against Dems as much as against Iran's leaders. With the latter, it's stop developing nukes or we'll attack. With congress, it's stop trying to end the Iraq war or we'll attack Iran. The questions are whether it's a bluff or they're really serious about doing it, and if they are serious, what congress is going to do about it.