Maybe this was Obama's plan all along. You could tell he didn't want to do this. If so, good show Mr. President.
The positive spin would be that this is actually all part of the plan to deter Assad from using chemical weapons again, without actually going through with an attack.
If the US and/or France actually attacked Assad with a few days of air strikes as punishment for using chemical weapons, then OK, maybe that would give Assad the message not to use chemical weapons again, because he would risk more punishing attacks from the West.
OTOH, maybe the attacks wouldn't end up hurting him as badly as expected. And they might have knock-on effects which could rebound to Assad's benefit. E.g., he can play on sympathy as a victim of Western agression, Iran and Russia might get more pissed off at the US, and redouble their support for him. Hezbollah might attack Western targets, or cause more spillover of violence into Lebanon. If the Western attack doesn't go well, then it might not end up being that big a deterrent against future chemical weapons use.
So is there a way that the West can scare Assad into not using chemical weapons again, without actually attacking him? Perhaps. If Obama talks tough, and goes right to the brink of war, but then doesn't pull the trigger because of the vote in Congress, then he has something of an out, and an excuse for not attacking. But he's explicitly said that he can go around Congress if he really wants to, which he'll threaten to do if there's a future provacation. So Congress votes down the use of force, and Obama says "OK, I won't attack now, but if there's another large scale use of chemical weapons by Assad in the future, then we'll attack immediately, without going through Congress."
The threat of retaliation is preserved, and Assad is scared away from using the chemical weapons again, because he's scared of the worst case scenarios for what might happen in a future Western attack against him....rather than being underwhelmed by an actual Western attack against him that doesn't go as well as planned.
