Sessions. All the others won their primaries.
This is incorrect. Pawlenty lost the gubernatorial primary in Minnesota to Jeff Johnson, who went on to lose the general election to Tim Walz.
Oh damn, forgot about that. You're right, T-Paw is a strong contender, especially since he'd been considered a serious presidential candidate not too long ago.
Bayh didn't technically win the primary either. Former Congressman Baron Hill did, and then withdrew a couple months later to allow the state party to choose Bayh as the nominee.