media bias?

Why is it that NPR seems so pre-disposed against the current Democratic candidates? Their editorial bent all week has been that the race between Obama and Clinton is a problem, and how sad it is that poor McCain isn't getting enough coverage.

My guess is that much of NPR's audience falls on my side of the political spectrum. While this doesn't necessarily suggest they should tailor their coverage accordingly, there seems to be a distinct editorial bias creeping in. When even the progressive commentators fall on the center-right end of the spectrum, I get the sense that they are trying to create "balance" by tipping the spectrum too far to the right.