The United States continues to be the most right-wing nation in the western world. While most western nations have prominent a staunchly left party (Canada has the NDP, Britain has Labour, Spain has the Socialists, France has the Socialists, and don't even get me started on Portugal. 128 MPs in Portugal are members of the Socialist Party, Communist Party, Green Party or Left Bloc!)
What I'm trying to say is that most western nations have a prominent leftist party (or in Portugal's case, several), while the US has none. Fox News will make sure anyone further left than Dennis Kucinich will get libeled if they ever attempt to run for president. Business in this country wouldn't allow it, either.
Parts of the Dems like Kucinich are leftist. Peace and freedom, Green party, Socialist Workers, Socialist party, are all leftist.