One question is why more governors don’t do this sort of thing. That is, why don’t they make state court nominations that will help broaden the Supreme Court (or at least federal circuit court) farm team? Given the salience of judicial nominations to the GOP base, this is a smart strategy for ambitious Republican governors. If you’re a Republican governor interested in running for the Presidency, and there’s a vacancy on the state Supreme Court, nominating a young conservative with a certain kind of resume signals to the GOP base that you “get” the issue. This has happened on occasion: Minnesota Governor Tim Pawlenty nominated former Thomas clerk David Stras to the Minnesota Supreme Court in 2010, soon before Pawlenty announced his bid for the GOP Presidential nomination. I don’t know that Pawlenty had his eye on the Presidency when he nominated Stras, but it wouldn’t surprise me. Either way, that sort of thing doesn’t happen very often.
One likely reason for the relatively rarity is that most state Supreme Court positions are elected rather than appointed. Even where there is an appointment, the Governor’s role is often limited. A second reason is that the politics and practices at the state level usually won’t make these national-level political considerations particularly salient. Still, when it happens, it’s an interesting way that today’s state governors can have an influence on a future President’s choices.