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by Mike Dorning
Sen. Bob Casey (D-Pa.) is to endorse Barack Obama today, according to Obama campaign aides, providing Obama with a prominent local backer in Pennsylvania weeks before an important primary there.
Casey is a socially conservative abortion opponent and gun rights suppoter popular among working-class white voters in Pennsylvania, a demographic group that Obama has not performed well among.
Casey is to to make the endorsement at campaign rally in Pittsburgh later today and then join Obama for the start of a six-day bus tour of Pennsylvania.