cnn: One out of every seven Democratic party voters was not registered as a Democrat at the beginning of the year, and 60 percent of them cast their ballot for Obama, according to the exit polls.
Sen. Hillary Clinton fared better with voters who made up their mind in the last week, the exit polls showed.
Fifty-eight percent of those voters said they broke for the New York senator. That includes voters who made up their mind in the aftermath of last week's heated Democratic debate.
obama looking ahead. he's got a rally in indiana tonight.
Calling Pennsylvania an "uphill climb," Obama declined to predict a victory in the state's primary Tuesday but said his campaign showed he can compete in a big state.
While saying that "we feel good about where we are," Obama appeared to be prepared for a victory by Clinton, and looking ahead to contests in Indiana and North Carolina.
"A win is 50 plus one. So, if Sen. Clinton gets over 50 percent she's won the state and, you know, I don't try to pretend that I enjoy getting 45 percent and that's a moral victory -- we've lost the state," Obama said during a stop in South Philadelphia.
"What I do believe is that we're coming to the end of this process. We've won twice as many states, we've won the popular vote by fairly substantial margins, we've got a very big lead in pledged delegates and we competed, win or lose," he said.