On Fox News Sunday this morning, Karl Rove threw cold water on the murmurings by unnamed “top Republicans” that a new candidate could emerge should Romney lose Michigan. Host Chris Wallace outlined a scenario in which a new candidate could still get on the ballots of California, New Jersy, Montana, New Mexico, South Dakota, and possibly Texas, and win enough delegates to contest the convention. But Rove was skeptical, to say the least. “This proves mental illness is transmittable by contact, personal contact. You’ve been talking to all these people and — look, let’s go. . . . Let’s take...