They wants someone on their side of the court who can stand up to Roberts, to bring Kennedy to their side. Kagan is smart, but she is an academic rather than a jurist. Roberts has been playing this game a lot longer. Obama, though, will get a third choice. Ginsberg cannot last much longer. Probably another woman , but maybe a pol.
Good observation. My bet is on the Hilarybeast. He gets to kill two birds with one stone. Kills 2012 competiton, and takes Clinton out the picture.