I think it would be wise to return to the UN and seek Security Council condemnation to chemical attacks in Syria, a determination of the party responsible, an inspection regime and, if Syria fails to comply, the authorization to use military force to degrade and deter the use of chemical weapons n the Syrian theater.
An example of the approach can be found in the UN resolutions in the 1990 Gulf War period which culminated in Resolution 678, which authorized the use of force against Iraq.
A parallel track can be pursued in the Congress. An example of the AUMF that might garner support would be the 1991 Authorization to Use Military Force Against Iraq (Desert Storm) which I discussed here. I would propose it along the following lines:
SECTION 1. SHORT TITLE.
This joint resolution may be cited as the `Authorization for Use of Military Force Against Syria Resolution'.
SEC. 2. AUTHORIZATION FOR USE OF UNITED STATES ARMED FORCES.
(a) AUTHORIZATION- The President is authorized, subject to subsection (b), to use United States Armed Forces pursuant to United Nations Security Council Resolutions regarding Syria's use of chemical weapons as may occur.
(b) REQUIREMENT FOR DETERMINATION THAT USE OF MILITARY FORCE IS NECESSARY-
Before exercising the authority granted in subsection (a), the President shall make available to the Speaker of the House of Representatives and the President pro tempore of the Senate his determination that--
(1) the United States has used all appropriate diplomatic and other peaceful means to obtain compliance by Syria with the United Nations Security Council resolutions regarding Syria's use of chemical weapons; and
(2) that those efforts have not been and would not be successful in obtaining such compliance.
(c) War Powers Resolution Requirements-
(1) SPECIFIC STATUTORY AUTHORIZATION- Consistent with section 8(a)(1) of the War Powers Resolution, the Congress declares that this section is intended to constitute specific statutory authorization within the meaning of section 5(b) of the War Powers Resolution.
(2) APPLICABILITY OF OTHER REQUIREMENTS- Nothing in this resolution supersedes any requirement of the War Powers Resolution.
SEC. 3. REPORTS TO CONGRESS.
At least once every 60 days, the President shall submit to the Congress a summary on the status of efforts to obtain compliance by Iraq with the resolutions adopted by the United Nations Security Council in response to Iraq's aggression.
With such a resolution, the President is empowered to go to the UN knowing the Congress has granted him authority to act militarily should the UN Security Council so authorize.
Now the retort I will no doubt hear is that Russia and China will never go along. That may well be. But we can find out, and if they do not, and do not in an unreasonable way, the Obama Administration will be able to honestly say they have exhausted all diplomatic channels and present to the American People these facts. This has not happened.
Beyond that, it will strengthen international support for the type of action the Obama Administration contemplates.
In my view, the biggest mistake the Obama Administration has made is instead of sending its diplomats out to rally support against Syria's apparent use of chemical weapons, it has instead sent its diplomats out to rattle sabers. This campaign has been counterproductive n the extreme. The Secretary of State in particular has been stunningly ineffective in his role. If this was the UK, his resignation would be in order. But he serves at the pleasure of the President.
In any event, I suggest a reboot along the lines described here.