The announce his intention to retire from the Senate. I don't think he has a snowball's chance of being elected governor again, but if he really hates being a senator...
The rumor was he almost did that to run against Justice when just ran for his second term. For whatever reason he decided not to. It depends who the state GOP gets to run against him. In his last Senate run the GOP’er was too easily painted as a carpetbagger.
Right now it seems he trying taken on the mantle of the new Byrd. We shall see.