This is why

Obama nominated Sonia Sotomayor:

Guido Calabresi said Judge Sotomayor’s forceful and lucid arguments had persuaded him to reconsider his position in a number of instances. "And I'm a tough act," he said.

Obama knows he's unlikely to replace any of the Court's reliably conservative bloc, even if he serves two terms.

And he's counting on Sotomayor to be more persuasive among her colleagues than perhaps Justice Souter ever was.

This is something barely anyone has mentioned in all of the thousands upon thousands of words devoted to Sotomayor already, as those authors prefer instead to concentrate on peripheral matters, including a goodly portion of mostly irrelevant nonsense.