by Patrick Appel
Nate Silver says the field isn't neccessarily set:
One seismic factor affecting Republicans’ decision is that Barack Obama is now exceptionally vulnerable for an incumbent president. If you’re a Republican and you think you can become president, that’s doubly important for you; not only does it mean that those aspirations are more likely to be fulfilled this time around, it also means that they’re less likely to be realized in 2016 or 2020 because there’s now more chance that some other Republican will already occupy the Oval Office by then.
Gallup's latest poll underscores Obama's vulnerability, but Jonathan Bernstein takes issue with Silver's larger methodology.
The Dish 