There were some good answers already. I try to give my opinion as a resident alien of the USA. As German, my own political preference would be center left, with a little green flavor in it. That would put me into the Dems corner in the USA, one could think, but it is not the case.
Both parties to me are too center right. My impression here is, that even tho in Germany party members also follow the codex sticking to the goals of the party they belong to, and usually always vote in that favor. But I know that German parties do throw out their own lower intentions when the country is in dire need.
The USA for example is in such need right now, a recession, borderline depression, yet the two parties are busy fighting each other toe to nail. I lived through similar times in Germany where the parties got together and said "screw this, none of us can fix this alone, we working together now, and created what we call in Germany a "great coalition". That's what the USA would need too. Both sides have awesome people in their ranks. Both sides have the capacity to fix whats wrong, together.
But both sides are rather busy to gain the sunny spot and slamming, and hurting each other where they can.
Most actual example.... On top of the recession, the USA suffers from the worst drought since 50 years. The farmers are in dire need for help. Where I live, in Iowa, I see miles and miles of fields withered, unusable anymore.. One would think the governemt will act. It did act.. the usual american way.....
Both, the Republican controlled Congress, and the Democrats controlled Senate came up with a relive program. Needless to say, both vary somewhat. And none of them passed. In order to pass for something it needs approval of both, House (Congress) and Senate... Custom however is, that whatever the other side comes up with, will automatically shut down by the opponent.
Now if the President would go ahead and says SCREW YOU ALL, ENOUGH WITH THAT, I enact my powers and do whats needed. You can bet anything you have, that there will be a very vocal group slamming him for acting like a dictator.... And since the current President is a Democrat, those voices will be republicans. Would he be Republican, the voices would be Dems...
As a foreigner in the USA, there are many things I cannot understand by common human sense.
Examples, like you mentioned the healthcare system. It should NEVER be challenged to strive for a healthcare system that's government funded.
To me it is a shame that the people of a country don't have any problem with their govt raking out billions and billions of dollars on warfare. It's perfectly fine to build military helicopters for 30 million a piece, but it's unacceptable for the govt to sponsor a healthcare program for ALL.
It's also a shame that the country resides behind 138 other nations in the world who grant their work force paid vacation of at least 2 weeks by law. In the USA that does not exist. In most cases people have unpaid vacation, and even that some don't have. Same goes with benefits at work, that are completely natural to any European, Americans don't have it.
In no other industrial country living so many people at or below the poverty line than in the USA.
The "non existent" gun laws, no one can understand that either..... People cannot see that there's a relation between the current handling and the high death rates through guns...
The stand on Prostitution, medieval viewpoints.. Whereas here too, crime statistics speak books. In countries (which is all europe for example) with legal prostitution the sex related crime rates are dramatically lower. Besides, Prostitute is a recognized job in many countries, means the prostitutes paying taxes just like with every other job.
They have to go through frequent health checks, required by law, and are safe.. Unlike crack whores in uncontrolled nations.
I quote George Carlin: "Selling is legal, fucking is legal, why isn't selling fucking legal? In the Army they give you a medal for throwing napalm on other peoples heads, in the civil world they put you in jail for giving someone an orgasm."
All in all, I cannot understand why the USA does not adapt ideas and handling from other countries, proven to work for decades. Instead the 2 parties are busy fighting each other and most importantly making sure nothing will ever change.....