If by 'left' we mean some variation on Communist, State Socialist, Libertarian Socialist or Anarchist, can you point to any commentators or columnists in the mainstream media that are one of those things or any newspaper or magazine or TV network. I can't. Mother Jones, or the Nation might fit close to some of those but they aren't mainstream. Hence the mainstream media is not hugely left. It only looks left from the far right.
There's no newspaper in the US that remotely resembles this:
http://en.wikipedia.org/wiki/L%27Humanit%C3%A9

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13