Republican U.S. Senate candidate Dave McCormick on Thursday appeared to declare victory in his race against Democratic incumbent Bob Casey Jr. despite The Associated Press not having called the race and the possibility that the narrow margin triggers Pennsylvania’s automatic recount process.

McCormick’s victory in the Keystone State marks a major win for the Republican Party and its projected multi-seat majority in the U.S. Senate.

Republican Dave McCormick appeared to win a major upset in Pennsylvania, beating three-term incumbent Bob Casey. The victory would give the GOP a key win in the U.S. Senate, where it now holds 53 seats.