Pennsylvania Sen. Bob Casey endorsed Democrat Barack Obama on Friday, a move that could help the presidential candidate make inroads with white working-class voters dubbed "Casey Democrats" in the Keystone State. Appearing on stage beside the Illinois senator, Casey told a boisterous rally, "I believe in my heart that there is one person who's uniquely qualified to lead us in that new direction and that is Barack Obama."
Pennsylvania's April 22 primary will allocate 158 delegates, the biggest single prize left in the drawn-out nomination battle between Obama and Sen. Hillary Rodham Clinton of New York. Clinton is leading Obama in the state, by 12 points in one poll this month.