I am with Fred Kaplan here, President Obma is right to seek authorization from Congress for any attack on Syria.
A question can be raised whether President Obama should have proceeded from the start in this manner. Possibly. But important point is, seeing what happened in UK Parliament, it was prudent to seek similar authorization from American Congress and that is what President Obama has done.
So what are the chances that such an authorization would pass? Those chances do not look good. Those are bit better in Senate considering Democratic majority there. As far as policy position on ideology goes, President Obama's middle path of limited action is coming under attack from both Right and Left. Military hawks like Sen. Lindsay Graham and Sen. John McCain have been upset for a while because President Obama has not been more interventionist. These hawks and neo-cons have been wanting President Obama to spend more of his political capital to follow footsteps of ex-President George Bush. President Obama refused so far but now he comes to Congress for legitimizing some limited intervention. That is 'too late, too little' for these neo-cons and one would not be surprised to see that these hawks vote down any limited intervention resolution.
The arguments on Left are reasonably simple - what happens in Syrian conflict does not pose any direct security challenge to us, so why bother? Whether Chemical Weapons are used or not; that is irrelevant. As far as international norms and accords of prohibiting usage of Chemical Weapons go; Left argues that "well, USA takes that responsibility when UNSC minds its own business". Basically, it is all about 'shrugging shoulders' and usage of Chemical Weapon is no special case.
Question for Republicans in House will be, what is the political upside in pulling British PM Cameron on President Obama and while they are snubbing him; what political price they would have to pay in future if any abnormal things like further usage of Chemical Weapons happen or terrorist would pull a chemical weapon attacks on American interests.
Being a second term President and the issue being of National Security it is possible that sufficient number of Republican House Representatives might find it OK to support President Obama's Syria intervention resolution. Yes, the extreme partisan politics of today's Washington has come to this stage - each Republican Congress member determining a vote based on how much it would harm/snub to the sitting Democratic President. If Republican Representatives and Senators determine that they still have something to gain by snubbing President Obama, they would do that regardless of how much it is a setback to nation's interests. Speaker Boehner and others are already laying the ground for Congress passing Syria resolution as the function of President's success in 'selling this intervention to America People'. Convincing majority of American people can be the sole responsibility of President Obama provided Republicans are going to vote in a faithful manner to reflect 'will of people and nation's interest'. As there is no such verifiable way to determine that, Republicans in Congress would have equally perfect opportunity to ambush President Obama as was done to UK PM Cameron. May be two equally snubbed leaders on both ends of Atlantic could sustain the otherwise damaged special relationship between USA and UK.