PHILADELPHIA (AP) -- As the clock ticks down on Tuesday's Pennsylvania primary, Hillary Clinton and Barack Obama are scrambling for votes in the Keystone State.
Pennsylvania's primary is the first in a month. And, with 158 delegates, it's the biggest single prize left in the battle for the Democratic party's presidential nomination.
Obama has a lead in overall delegates and a thin edge in the popular vote. Clinton is hoping to end up with the popular-vote lead to persuade the uncommitted "super-delegates" to back her.
Yesterday, Obama launched unusually sharp attacks on Clinton's character. He said she's a "slash and burn" game-player who will say whatever people want to hear in order to win.
Clinton portrayed the race as a choice between flash and substance, urging Pennsylvania voters to look beyond what she called Obama's "whoop-dee-do" speech-making.