Verified answer

No, it's more of a courtesy, and I'm pretty sure Obama wouldn't do it if he had any fears that Congress would reject his request. It's a little like the Iraq War resolution that Congress obligingly passed for GW Bush - who would have gone to war anyway even if it hadn't passed. This administration has always held to the line that presidents have held since at leas the Nixon administration - that it is within the powers of the presidency to deploy the armed forces without Congressional authorisation.

Naaaa he just wanted to see if congress could take the blame off him for a bit