South Dakota Senator Tim Johnson's doctor is telling CNN that, yes, he'll be able to work in the Senate again.

Yet though Johnson may be on the mend, he's already got to start worrying about facing a challenge next year. As Steve Benen notes, John Ensign, the National Republican Senatorial Committee chairman, is already telling The Washington Post that there are several potential challengers waiting in the wings, including Republican Governor Mike Rounds.

Ensign says that they've already talked "a lot" to Rounds about targeting Johnson. How long after Johnson fell ill did they start talking about this? We'd love to know.