In my opinion, the mechanism we're watching is the irrelevancy of the early race becoming more and more transparent. We're discovering that the early vetting is actually counter-productive as it allows unviable candidates to consume a lot of resources without any real chance of winning a general election. We're discovering that the lunatic fringe, which cares a whole fuckload about politics, has no effect on that muddly middle of undecideds who will generally vote for the most charismatic, least crazy individual.
Bush was a legacy; he was also the establishment favorite of a large apparatus of party politics. We haven't had a favorite son like that since; I mean, yeah, Jeb, but that only shows that they managed to grind the Bush name down to nothing. You look at the field now and none of them make as much sense as Gingrich or Huckabee or Santorum and none of them made much sense. In the end it came down to Romney because he looked kind of like a president and walked kind of like a president and people could see it, just not quite clearly enough to want it. That's where Clinton is - most anyone over 30 remembers her husband doing kind of a pretty good job, and that's probably enough. That's what's gonna get Sanders in the end - he's LaRouche Lite. That my own personal politics align clearly with him does not temper my pessimism about his chances. Maybe if OWS were active and in the news right now he'd have a chance. But in the end, it comes down to "not crazy, likeable, credentials for the job."
Rand Paul on Solyndra doesn't f'n touch Gingrich and his moon bases, by the way. "Obama's crony capitalism is wasting your tax dollars on hopeless liberal fantasies" comes from the same place as Reagan taking down Carter's solar panels just to prove a point. "I'm gonna pretend we're at the height of the Cold War and blow trillions on symbolism in the name of pork" is a gonzo move, particularly from the king of congressional shutdowns.
Although... Space.com put the cost of a moon base at $35 billion. The ISS cost us $100 billion. For the price of the F-35, we could have eleven of each.