I guess if Khameini or Olmert provokes it because Bush did not seem to be interested in OTL. Gravel could then edge Obama out with emphasis on his experience and Hillary with her Iran War vote.A war with Iran might help.
I guess if he ran for his Senate seat again and unseated Lisa Murkowski by accusing her and her father of nepotism.Would there be a way to get him back into the Senate or something at some point so he'd seem more relevant and experienced?