The historical trend can be seen at this link.
I personally will vote for Obama if Edwards loses out because Hillary represents the past and she represents the worst of the Beltway Establishment: the DLC, the Shrumites of the world, the lobbyist wing of the Democratic Party.
That said, Obama smacks of Establishment Lite per his Iraq War comments and pandering on so-called "faith-based" groups (which require a sponsor at schools which of course hurts minority religions).
John Edwards is the future for that sea of middle Americans pining for change... Edwards/ Richardson 08!!!