I think he's gotten plenty of support from Congress on his plan to replace secular leaders with radicals in the region, it just hasn't been made public. Most in Congress share Obama's vision of the destruction of Israel, as do most liberals in general. Most liberals also despise Christians, and they see the rise of the Caliphate as a move forward in their progressive world.
Then let them take a public vote on the Authorization for Use of Force.
Absent that, we should hope they come to their senses and get US forces out of harms way.
There is absolutely no legal basis, US or International Law, for US Forces to be engaged in Syria...another Sovereign Country that Obama decided, unilaterally, to destroy.