I'm intrigue with the "or else" part of it...what could possibly happen, in the scenarios of the US playbook, that "or else" can lead to?
Or else US is going to suffer collateral damage. The only way US is going to suffer least damage in this affair is keep the lines of communication open and the matter resolves itself without either side held US responsible for favoring the other side.
The traditional ways of resolving the issue when you cannot talk the parties involved out of it are offering bribe or issue threat. Unfortunately, neither is feasible right now.
Any bribe Obama administration promised cannot be delivered because he does not have the political capital to force the issue. Even if it's something agreed to by the Republicans, someone is going to attach a rider to it -- and chances are that it's something Obama does not like. So that leaves the threats.
Threatening either side is expensive in either case --
Taiwan: Any economic threat will be more then make up by China. Withhold arms sale? Didn't you want to strength Taiwan against China? And Taiwan is no longer flushed with cash -- so they may take the opportunity to save some money. And any sign of favoring Philippine will be tremendously damaging to rabidly anti-China DPP, and gave China an opportunity to profit from this.
Philippine: kiss your pivot goodbye and forget about new bases in Philippine. Only a treaty ally can taunt China in relative safely -- and that is only when US retains naval supremacy. Don't expect Vietnam to continue the pivot alone -- it knows from experience (1979) that even a superpower cannot save it if it pisses China off. No one sane wants to fight a land war with China on its borders.
So the best option for US, again, is keep the lines of communication open and hope the situation resolves itself -- without anyone holding US responsible for favoring the other side.