Hard to even begin to understand, maybe you have to be American, but something I was once told, and which is a very good start, is that American politics is nothing at all like UK, or even European politics.
The Republican and Democrat parties are best likened to the right and left wing of the UK Conservative party. There is nothing like the Labour party in the US, despite sometimes Labour thinking the Democrats are somehow on their side.
The calling of Obama a "socialist" in America, is meant as an insult. Maybe it's like someone here calling Milliband a "Communist"