Obama just gave a speech that he is now seeking Congressional approval for a strike on Syria. If you have watched any of the White house press briefings the last week you know that every time this question came up they would say "we will consult with congress but we believe the president has the authority to order a limited strike on Syria".
Although there are some in congress that believe he needs approval, most democrats and republicans think he had the authority as did Reagan, Clinton and Bush1. So why seek approval?
Obama really got himself in a pickle by drawing this red line and got heat from some republicans, but mostly from democrats and his base of anti-war opponents.
It was a no win situation.
This gives him the political cover he needs, If congress does not give him approval, he can back down from his red line statements saying"I wanted to strike, but congress stopped me". If they approve and it breaks out into a full scale war where Assad and Iran attack Israel and Jordan to retaliate, he can say that congress approved this action.

What I find interesting in his closing statement was he said "this isn't about who is in this office, but what our country stands for".

Seems he is already framing this debate by his usual tactics,
If your against this action it's because your a bigot or don't like Obama. JMO

maybe it wasn't Corner-Painting,but his usual calculated Political Tricks!
Under the Constitution,he doesn't have the authority to go to War,unless the Security of the US is at stake!
And even then he is only allowed limited action!
He's pulled the Limited Action Stunt in Libya,and Congress let him get away with it,even though it didn't apply there!

Your right of course, but Reagan, Clinton and Bush1 have all used limited military action without facing criminal or legal action from the congress. It is generally an unspoken rule that he needs congressional approval for an action lasting more then 60 days(based loosely on the War Resolution Act). Having said that, if congress is completely against a military action they can immediately pull the purse strings and the president won't have the funds to launch a strike.