To state what I think should be obvious, talk of Evan Bayh somehow challenging Barack Obama for the 2012 Democratic nomination is bizarre. No incumbent president has ever been defeated in a primary. And the only “close calls” came in a tightly bunched historical period (1968, 1976, 1980) characterized by substantial transformation of the regional bases of the major political parties. On top of that, successful primary challenges to incumbents are invariably driven by base-oriented candidates knocking off incumbents who’ve strayed too far off the reservation. And ideology aside, Bayh is no Ronald Reagan or Ted Kennedy. He’s a well-known Senator inside the Beltway (not an invisible man like Crapo or Kohl) but he has no national profile whatsoever. And he has no means by which to raise the funds necessary to acquire such a profile.
On top of all that, there’s just no sign that Democrats have any problem with Barack Obama. His job approval rating is hovering a bit above fifty percent meaning he would need to fall much, much further for him to be in any kind of danger with self-identified Democrats.