I doubt this gets too messy. Fact is Assad is going to have to go at some point. The question is how long do we want it to take. I don't see how small arms and anti tank missiles will turn the battle but I guess it could. IMO you need some air strikes.
Remember Iraq was a cakewalk but Bush decided to try and play Rome and rebuild the place. As long as Obama doesn't care about the infrastructure or security of the govt he leaves behind he can finish assad rather easily I would think.
Its more he wanted to try and have a great 2nd term. I doubt all these scandals then another war is really great for that 2014 liberal turnout.