There are no leftists on American television
One of the reasons that the political discourse in the United States has shifted so far rightwards is because of televised crap like Crossfire and The McLaughlin Group. These shows generally consist of some number of people representing "the right" and some number of people from "the left". Only, while the rightists on these shows are quite conservative, the "leftists" tend to be moderates who happen to be Democrats. Thus, the beliefs on "the right" range from Pat Buchanan to John Sununu, while "the left" is represented by Bill Press or Al Hunt.
This is not an accurate reflection of the range of political beliefs in this country!
Where is Alexander Cockburn? Where is Christopher Hitchens?
As long as the media conglomerates can control public discourse in America, they can continue to manufacture consent and avoid any obstacles to the increasing power of large corporations.