Matthew Yglesias and Dave Weigel catch Byron York making the transparently stupid argument that Barack Obama's positions "appear a bit more popular overall than they actually are" because of his "his sky-high ratings among African-Americans." As Yglesias notes: "How does the fact that much of Obama's support come from African-Americans mean that he's not 'actually' popular?"
You'd have to try pretty hard to come up with an explanation other than racism for York's position that support among African Americans shouldn't count as much as support from whites.
But York's argument, though absurd, is actually quite consistent with the way the media in general approaches public opinion.
When reporters talk about Democrats' difficulty appealing to religious voters, for example, they mean white religious voters, and point to polling of white evangelical voters to support their claims.
When they talk of Democrats being out of touch with "regular people," they aren't talking about working-class African Americans or Latinos; they are talking about white regular people.
York's comments about Obama's support is just one example of the media's habit of equating public opinion among whites with public opinion.