The only one in the race with a national constituency is McCain, and he's too close to Bush to win in the general election.
The news media absolutely refuses to cover the news. They only want to talk about the immediacy of the horserace. The news is that Bush is staggeringly unpopular and all the Republican and conservative policies have failed. The GOP base is small and splintered. The Democrats have done a terrible job building a base, but they're competent, moral and honest (comparatively speaking) and are reaping the benefit of the anger at three stolen elections in a row and 12 years of the sleaze and corruption during the Gingrich/Bush reign.
This isn't about "segments" of people, this is about how democracy works. And it ain't pretty.
As I've been saying for a while, I'm not looking at the results of the too-early races, but the turnout. And it looks good for the adults.