Pound for pound, Centrism is the biggest and most debilitating lie in American politics bar none. It is the Big Lie that makes all the little lies possible, which is why I focus so hard on those who traffic in it. They are the ones most vulnerable to and terrified of being called out in public. They are the ones we must run out of the media on a rail.
Rightardia agrees that the so-called "left" in the US is equivalent to the center in Europe. The Democratic Party in the US has more in common with centrist Liberal Party in the UK than the left wing Labour Party.
There is a Green Party in Europe that wins seats in legislatures. In the US we have a club in the US that advocates environmental issues, the Sierra club.
Socialism is a dirty word in the US and nearly six in ten Americans have an unfavorable view of this -ism: See http://www.gallup.com/poll/125645/socialism-viewed-positively-americans.aspx