Pennsylvania voters might produce a surprisingly close outcome in today’s Democratic primary. The buzz in Washington from several Democratic operatives I talked to yesterday suggests Team Obama is fired up and ready to over perform. “They’re putting out the word they won’t win, but it will be close,” a veteran Democratic operative told me. And in this expectations game, “close” is a win, especially since Clinton needs a 8-10 point win to keep her narrative alive. They must see something in their tracking numbers that suggests the race has tightened. Jeanne Cummings’s piece in Politico yesterday supports this view. She looks at the surge in voter registration over the past four months and some evidence that much of that increase is tilting toward Obama.