Don't know, they like to be "saviors" and there is still a long time for 0bama to make things worse. The party would want to avoid seeing a landslide loss that would destroy the Left for the next 20 years.
In fact, the only way I see the Rats coming close to being able to win again is to call Obama incompetent and putting someone else up.
There are no signs that the Clintons are preparing for such a challenge and the hour is growing late. We would see signs by now.