Dave McCormick wins US Senate Race in Pennsylvania: AP

David McCormick has been elected to the U.S. Senate, unseating longtime Sen. Bob Casey and marking another Republican win in the swing state, AP reports.

The race was called nearly 48 hours after polls closed in Pennsylvania, but razor-thin margins made it too close to declare a winner as vote counting continued.

McCormick entered Thursday leading by .4 percent with 98% of the ballots counted. They hoped ongoing vote counting in Cambria County would tip the scales.

"McCormick is up 30,679 votes with more to come, as ruby red Cambria County is still outstanding," Communications Director Elizabeth Gregory said. 

"Any way you slice it, Dave McCormick will be the next United States Senator from Pennsylvania."

McCormick's campaign was billed as "the strongest challenge" to Casey's attempt at a fourth term.

Casey has not conceded the election, saying in a statement that there are "tens of thousands of ballots across the Commonwealth still to count."

"This race is within half a point and cannot be called while the votes of thousands of Pennsylvanians are still being counted," a statement read.

Meanwhile, the PA Department of State's Secretary Al Schmidt said in a statment to X, formerly known as Twitter, that they estimate there are at least 100,000 ballots remaining to be adjudicated.