>I don't know that Biden's odds of holding the top position are really slimmer than McCain's VP. If you mean actuarially based the ages of McCain and Obama, I'm sure that's true. But I think there is a much higher than usual chance Obama will be assassinated if elected.

Obama asassination story is lingering in the air quiet long.
http://www.dailymail.co.uk/news/article-513512/They-kill-Obama-US-president-Outcry-Nobel-Prize-winners-assassination-warning.html