The USA could totally win in the middle east, but nobody has the stomach anymore for that. Just think of the level of force used by the allies to subdue both Japan and Germany in WWII. Could anybody actually get away with carpet bombing cities, executing enemies, and nuking two cities nowadays? But they could do all that and spend another 20 years there beating it into everybody's heads that you can't pull that crap anymore, and then probably win. But we in the west see these images in the news, and hear about it on facebook and twitter, and most people go we shouldn't be doing that, it's not civilized.... because beheading people is......
As far as the election in the USA, they are screwed either way. Pick the one that might screw you but your not sure or the one that has before.
Yeah, sure, pour even more untold amounts of money in a ruinous war that will last for decades (unlike Germany and Japan, there is no central authority in the Middle East that can surrender to the US this time), perhaps not even solve the problem in the end as you just fuel even more martyrs to the cause, alienate most of America's allies in the region, to say nothing of that fact that Iran could potentially also have and/or use nukes if pushed, and Pakistan (which is also part of the larger problem) actually does have them, too, so they can push back if desperate.
Nukes changed the game completely. Total war is no longer an option. Vietnam also changed the West's outlook towards warfare, we can't just pretend it's heroic soldiers doing brave stuff all day long in the name of truth, justice and the American way anymore. It's brutal, shitty and kills innocents more than anyone else.
All-out war also didn't work for the Soviet Union in Afghanistan, and they certainly weren't shy with using every tool in their shed. Didn't work for France in Algeria either, just like it didn't work for the US in Vietnam. Some problems can't be solved by just killing more people, unlike what Hollywood action movies teach us.
Plus, in a coldly realpolitik way, the US isn't suffering from the troubles in the Middle East that much. What do they lose since they mostly left, a few soldiers or ''advisors'' here and there, with the occasional kidnapped journalists, two whole terrorist attacks where one was basically because the guy was a self-hating gay dude, and one fuck-up at Benghazi that killed more people. Sucks for those people sure, and I'm not saying they should take it lying down, but that's far from something that justifies total war. In the end, they probably benefit from the wars in fact, since they are now defusing tensions with one of the region's main powers (good for diplomacy and, of course, moar markets), keep the Muslims fighting each other rather than Israel or Saudi Arabia, and rake in all the juicy oil by playing the guardian angel to a variety of regimes.
Europe suffers from the wars much more, by way of increased terrorist attacks and now the refugee crisis. The US are sufficiently far that they barely feel the aftershocks.