The U.S. Senate election in Pennsylvania between Democratic incumbent Sen. Bob Casey and Republican David McCormick is headed for a statewide recount, as counties continued Wednesday to sort through outstanding ballots and the campaigns jousted over which ones should count.

Republican David McCormick cut into Democratic Sen. Bob Casey's support in Philadelphia and its populous suburbs and built leads in the more GOP-leaning parts of the state, foreclosing the incumbent's pathway to victory when The Associated Press called the race Thursday.

The incredibly tight Pennsylvania race between Democratic Sen. Bob Casey and Republican challenger Dave McCormick will head to a recount, Pennsylvania Secretary of the Commonwealth Al Schmidt announced Wednesday.