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.

McCormick sought to portray Casey as a do-nothing politician who had served 18 years in the Senate and had few legislative victories. Casey attacked McCormick for leading a wealthy hedge fund that sometimes invested in China and for giving a misleading picture of his record as CEO of a company in Pittsburgh.