Rush is spinning this statement on the radio but it won't get traction except with the already converted fan base. What Biden did here, IMO, is the same kind of spin that Rush does for the Reps. Biden characterises a popular Democrat and possible POTUS candidate as 'mainstream' thus it attempts to plant a seed in the public's mind that Obama (and by implication Democrats) are the mainstream whilst, say, black Republicans (and by implication Republicans) are not.