It amuses me that my fellow Americans don't seem to realize that in elections you have the choice between the somewhat-far-right (Republicans) and the center-right (Democrats). I'd hate to see what kind of reaction an actual progressive/liberal party (with mainstream support) would garner if it emerges.
edit:
For example, consider this picture:
This image is from
www.politicalcompass.org, where one can fill out a survey and be listed on a two-axis political graph. As you can see, on both economic and social issues, Barack Obama and all the major Republican candidates are very close together. An actual person who supported State Property would find him self more or less completely opposite of Obama on the economic scale, while a mere socialist would find himself more towards the center.
tl;dr American politics are incredibly right-wing compared to most other countries (but especially the 1st world) on Earth, Democrats/Obama are not socialists/communists.