As vote counting continues this week in Pennsylvania’s tight Senate race, attention is once again shifting toward the largest and most hotly contested tranche of remaining votes that could help Democratic Sen.

Republican Dave McCormick won the U.S. Senate election in Pennsylvania, Decision Desk HQ projected on Thursday, beating Democratic incumbent Bob Casey in an important win for Republicans hoping to capture a majority in the chamber.

The U.S. Senate race is going to an automatic recount, requiring already exhausted election officials to reprocess seven million ballots in under two weeks.