In the Democratic Primary, the last two candidates, Obama and Clinton, represent the left of the political spectrum. Supposedly. In an article by Christopher Hayes in The Nation, he writes that the last two candidates standing are not discussing issues important to progressives. According to Hayes, what the two candidates are not discussing include

calling for the nation to renounce its decades-old imperial posture or to end the prison-industrial complex; neither is saying that America's suburbs and car culture are not sustainable modes of living in an era of expensive oil and global warming or pointing out that the "war on drugs" has been a moral disaster and strategic failure, with casualties borne most violently and destructively by society's most marginalized and--a word you won't be hearing from either candidate--oppressed.

Hayes makes valid and important points. Hayes, in short, is letting us know that Obama and Clinton are really not liberal enough. Similar to what McCain and Romney are battling out to see who is or isn't conservative.