Nah, they won't. Congress is just fine with killing babies. Congress is not even ashamed of killing babies.
The Syria hawkish minority is very loud but otherwise not very impressive. It won't be like 95-0-5 or anything stupid like that, but it's not gonna pass the Senate. It stands even less chance in the House just because it would be Obama who was allowed to order it.
Edit: I don't mean he pulled a Slick Willy. I mean that speech makes him come off about as well as he can possibly come off barring a time machine and changing his statement of "red line = u git bombed" to "red line =" well, basically anything else. And you know, there's still not even much consensus that it was Assad's regime that crossed that line to begin with. So if the UN reports come back that it wasn't Assad, that speech makes him look strong instead of weak. If I was a little more of a conspiracy theorist that would make me wonder if maybe Barry knows something that he's not letting on.