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.

Republicans are going to court in Pennsylvania amid vote counting in the U.S. Senate election between Democratic Sen. Bob Casey and Republican David McCormick, with the contest headed toward a state-mandated recount.

Republican David McCormick is projected to defeat Sen. Bob Casey (D-Pa.) in one of the nation’s preeminent battlegrounds, according to Decision Desk HQ, adding to the party’s margins after it took back control of the upper chamber earlier this week.