Garance wonders whether congressional authorization will create “a more aggressive or protracted intervention than what we’d have seen had the president not sought Congress’s buy-in”:

[I]f Obama gets congressional approval, he’ll be getting it in what is likely to remain a fairly open-ended way, as part of a strategy with bigger aims, and owe his legislative success in part to the support of the most hawkish members of Congress. Is there any doubt they will continue to pressure him to act under the authorization they will have granted him, and that his White House requested? And that the forces gunning for intervention, once mobilized, will have a momentum of their own?

Chait argues that Congress voting against authorization might deter Assad from further use of chemical weapons:

Imagine that Congress votes not to authorize Obama’s plan. Then further imagine that Bashar al-Assad, emboldened, carries out another chemical attack. The media coverage would be far more intense. And members of Congress who voted no will have to answer for the carnage that will appear on television screens across the world. If the first vote lost by a relatively narrow margin, Obama would probably then call for a second vote and stand a good chance of winning.

The prospect of that happening may itself deter Assad. And when Republicans complain that Obama’s gambit of asking for a congressional vote is a way of shifting responsibility onto Congress, they are, in a sense, correct. Obama will own the consequences of action with or without Congress’s approval. But if it disapproves, Congress will own the consequences of inaction. And those might ultimately prove higher than it is willing to bear.