With John Paul Stevens "likely to retire by the end of the month," Ambinder reads the tea leaves:
The legal cognoscenti believes that [Elena] Kagan, the solicitor general, has the inside track, with some folks swearing that Obama has already decided on her, and that he'll simply go through the motions again. It's not unreasonable to assume that Obama had his SCOTUS picks mapped out from the beginning of his presidency: the guy is a student of the Court, and he has a very particular theory of the types of justices that would best ensure that his vision for the court is appropriately articulated.
Sotomayor's pick was about changing the narrative. The second pick will be about adding some intellectual creativity to the mix. One reason he might not pick an appeals court judge this time is that appeals court judges tend to constrain themselves to precedent a bit more than Obama believes is necessary, while long-serving district court judges, or academics, are likely to be more expansive in how they approach the job.