Yes thats a bit worrying. The most obvious reason for him doing that is that he thinks he will win the vote. After all, he stated quite clearly he believes he has the power to order an attack on Syria without congressional say so. So, he is going to come out of this not so bad. If congress say yes, then he can shift the blame for the coming debacle and all the negative political pain onto them. If they say no, he can look like a statesman like figure who bravely deferred to the American people to guide his actions (which is what he should be doing anyway, but never mind).
Will the attack take place? Fifty-fifty. Not that it matters anymore (except to some poor folk in Damascus who might cop a tomahawk missile).