As in any other field, so, in Prez politics i.e. gut feeling of Obama. As is very well known Mac was Republican nominee way before Primaries of Democrats were decided. But that proved to be undoing of Mac as the day he was nominee, Obama's instincts told him that he can defeat Mac. And Obama never looked back from that day and managed to defeat Hillary. AND REST IS HISTORY.
Besides this here are other tit bits:
1. Some1 on 1 of the news ch (?Fox) said that Mac does not want to win. Only Mac can answer that question. But there are a few corroborations to it e.g. his treating Obama with disdain during the 1st debate whereas the same Mac was changed person in the 4th unofficial presentation in front of Press organized by Arch Diocese at New York.
2. Though Sarah was the best pick for VP yet I read an article that Sarah was wasted and I agree. Mac, perhaps, spent way too much time in her grooming rather than throwing her to wolves. However, Mac will be remembered for bringing Sarah to fore and more so, if in 2012, she is the Republican nominee.
Here comes 1 SUGGESTION:
Why not in future, there should be cross debate between VP nominees and Prez nominees.
3. Last but not the least Mac should have never withdrawn from MichiGAN as that was read as surrendering to economic distress from which he could never make stage back and I am told that Sarah sent him email that you don't have to do that.
