Sen. Bob Casey, D-Pa., on Thursday conceded the race for Pennsylvania's Senate seat to his Republican opponent, Dave McCormick.

NBC News projected McCormick's win shortly after Casey's concession. The slim margin of the race had triggered an automatic recount, with results expected to be released Wednesday.

"I just called Dave McCormick to congratulate him on his election to represent Pennsylvania in the United States Senate," Casey said in a video on X. "As the first count of ballot is completed, Pennsylvanians can move forward with the knowledge that their voices were heard, whether their vote was the first to be counted or the last."

McCormick thanked Casey in a statement, saying Casey has "dedicated his career to bettering our commonwealth."

"I am so honored to represent every single citizen in Pennsylvania in the United States Senate and will fight for you every day," he added.

McCormick had declared victory earlier this month after The Associated Press called the race for him. Casey, though, had held out hope as ballots were counted, even as Republicans criticized him for waiting to concede.

With 99.8% of expected votes counted, McCormick had 48.8% of the vote to Casey's 48.6%. The candidates are separated by just over 16,000 votes.

McCormick's win pads Republicans' narrow majority in the Senate, which is at 53 seats for the next Congress. His victory could make it easier for President-elect Donald Trump's Cabinet picks to be confirmed.

Republicans will control the White House and majorities in both the House and Senate starting in January.