Casey, 64, is a stalwart of the state’s Democratic Party, having won six statewide elections going back to 1996. But the vote count early Wednesday morning were suggesting that could change.

One of Pennsylvania’s two U.S. Senate seats is before voters Tuesday. Incumbent Democrat Bob Casey is vying for a fourth term against republican challenger and businessman Dave McCormick. Let’s start with incumbent Senator Bob Casey.

Democratic Sen. Bob Casey and Republican challenger David McCormick face each other in Pennsylvania's high-stakes U.S. Senate contest.