To even suggest that America has a political party which is so much as left wing is ridiculous. You have to look on it in a historical sense, not the immediate sense, because this sense is always distorted and perverted by the current circumstance.
We take America with its two major political parties, Reps and Dems. Both wholly concerned with corporate interests.
So, now look at the parties in their immediate, non-historical position in the political spectrum. Yeah, the Dems may be more toward the left, than the Reps. But they are still incredibly right wing, in a historical sense. Communism can only be observed in a historical position. Because it has never existed. In theory it is to the extreme left, the Dems and Reps are both to the extreme right, again, in a historical outlook. So to even link those two together is ridiculously absurd.
Maybe this will help in terms of Immediate and historical human ideology.
Historical
LEFT--------------------------------------------------------CENTER----------------------------------------------------------RIGHT
Communism------Socialism-------Liberalism-------Centralism-------Conservatism-------Capitalism--------Fascism
Immediate sense (Existing in the current U.S empire)
LEFT-------------------CENTER----------
Communism------Socialism-------