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.

The win by McCormick, a wealthy ex-hedge fund CEO, marked the culmination of a decade-long Republican effort to oust Casey. It also means the state’s representation in the Senate will be split, as it had been for the 12 years before Sen. John Fetterman’s (D-Pa.) victory in 2022.

Casey had led throughout much of the campaign, though that lead narrowed in the final weeks. According to an Emerson College poll, he led by a single percentage point two weeks out from Election Day.

The race was one of a handful of key states where Republicans were hoping to flip seats occupied by Democratic incumbents. With Pennsylvania, the GOP managed to flip four Senate seats: The other seats include Montana, Ohio and West Virginia. Democrats managed to hold on to their seats in Nevada, Wisconsin, Michigan and Arizona, which is currently held by retiring Sen. Krysten Sinema, who switched from Democrat to independent in 2022.

Throughout the campaign, national Republicans were clear-eyed about the difficulty of beating Casey, yet they believed the Pennsylvania race could be won with the mix of the right candidate and enough money to counteract the well-funded incumbent.

They recruited McCormick, who lost the 2022 GOP Senate primary to Mehmet Oz, shortly after Oz’s loss to Fetterman in the general election. Republican leaders helped clear the field for him to avoid a bloody primary battle and have a clear shot at Casey.

The GOP nominee attempted to frame Casey as a do-nothing senator who has achieved little throughout his 18 years in office and has been little more than a rubber stamp for President Biden’s agenda.

“You are a weak senator, you’re a liberal senator, you’re a career politician who wants to have it both ways,” McCormick told Casey during their first debate in early October.

Casey, in turn, sought throughout the campaign to paint McCormick as a multimillionaire carpetbagger who lives in Connecticut and shorted Pennsylvania companies during his time running the hedge fund.

“If he’s going to talk about his record versus my record, his record is as a hedge fund CEO investing in China and our adversaries,” Casey said during their second debate in Philadelphia. “That’s his record. Mine is bipartisan work in the Senate.”

McCormick has frequently referred to himself as a “seventh generation Pennsylvanian” and says that he has lived in the state during both of his Senate races. However, he has noted that he lived in Connecticut while working at Bridgewater Associates, one of the world’s largest hedge funds. His daughter from a previous marriage continues to reside there.

That added to what was believed to be the difficulty of beating Casey, who has proven to be difficult to oust. After defeating then-Sen. Rick Santorum (R-Pa.) in 2006, Casey won his next two reelection bids by 9 and 13 percentage points, respectively.

Casey is also part of Pennsylvania political royalty. His father, former Gov. Bob Casey Sr. (D), served two terms in Harrisburg and was considered one of the most prominent anti-abortion Democrats.

The sitting senator has had a checkered history on abortion, which has culminated in him being a full-throated backer of abortion rights — a stance McCormick and Republicans repeatedly tried to use against him. Casey has said that he supports scrapping the 60-vote requirement for legislation in order to codify Roe v. Wade protections.

“There’s no senator who flip-flopped on abortion more,” McCormick said during the first debate, having pointed to Casey previously labeling himself as “pro-life.”