Republican Pennsylvania Senate candidate Dave McCormick was declared victorious in his high-stakes election against longtime Democrat Sen. Bob Casey on Tuesday. 

Casey’s campaign released a statement Thursday afternoon saying he would not concede until all votes are counted. 

“As the Pennsylvania Secretary of State said this afternoon, there are tens of thousands of ballots across the Commonwealth still to count, which includes provisional ballots, military and overseas ballots, and mail ballots,” Maddy McDaniel, a spokesperson for Casey’s campaign, said in a statement. “This race is within half a point and cannot be called while the votes of thousands of Pennsylvanians are still being counted. We will make sure every Pennsylvanian’s voice is heard.”

As of Thursday afternoon, The Associated Press was reporting McCormick with 3,340,649, or 49.0% of the vote, and Casey with 3,308,961, or 48.5% of the vote. 

Casey has served in the Senate since 2008 and ultimately became a stalwart within the Democratic Party. For example, he voted on legislation President Biden supported 98.5% of the time, according to FiveThirtyEight data.  

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The Casey name also has deep roots in the state, with Bob Casey Sr., the senator’s father, serving as the Keystone State’s governor from 1987 to 1995 after years of serving in various other elected roles.

The longtime senator, however, faced what was described as his most difficult re-election effort to date, squaring up against Republican businessman Dave McCormick. 

McCormick is an Army combat veteran and former CEO of hedge fund Bridgewater Associates who served as the undersecretary of commerce for industry and security as well as undersecretary of the treasury for international affairs in former President George W. Bush’s administration.

Political eyes have been locked on Pennsylvania this election cycle after it yet again emerged as a key battleground state for the presidential race. Trump narrowly won the state in his successful 2016 election against former Secretary of State Hillary Clinton, while President Biden declared victory in the Keystone State in the 2020 election. 

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The race was rated as “leans Democrat” by both the Fox News Power Rankings and the Cook Political Report, with Casey himself acknowledging this year that it would be a “close, tough race.”

Biden campaigned for Casey in their shared home state, with the president lauding the senator as “a man that kids can look up to.” On the other side of the aisle, McCormick earned Trump’s endorsement. 

“He’s a good man. He wants to run a good ship,” Trump said during a rally in April. “He’s a smart guy. He was a very successful guy. He’s given up a lot to do this.”

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The two have sparred over issues such as immigration, abortion, spiraling inflation and law enforcement in their campaigns and during their debates.

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Casey campaigned on a platform of protecting access to abortion, lowering “greedflation” and preserving Pennsylvania’s “energy legacy” while also working “to protect our environment” and bolstering infrastructure in rural areas.

McCormick campaigned on reeling in inflation under the Biden-Harris administration, securing the border, curbing crime, defending the Second Amendment and expanding the Keystone State’s energy sector.

The high-stakes election put both candidates under the national spotlight, including earlier this year when police leaders in the state slammed Casey for aligning himself with a pro-defund the police group as he geared up for the election. He was also dinged by McCormick and other conservatives for rhetoric blaming spiraling inflation on corporations’ alleged greed, which he calls “greedflation.” 

McCormick came under fire from Casey and Democrats for splitting his time between Pennsylvania and Connecticut, where his children attend school, painting him as a Keystone State outsider.

Get the latest updates from the 2024 campaign trail, exclusive interviews and more at our Fox News Digital election hub.  

Fox News Digital’s Bradford Betz contributed to this report.