Senator Bob Casey concedes the Pennsylvania Senate race to Republican Dave McCormick

Sen. Bob Casey, D-Pa., lost the Pennsylvania Senate race to Republican opponent Dave McCormick on Thursday.

NBC News projected McCormick’s victory in the closely contested state shortly after Casey’s concession, further strengthening the GOP’s newly won Senate majority.

“I just called Dave McCormick to congratulate him on his election to represent Pennsylvania in the U.S. Senate,” Casey said in an interview. video on X. “Once the first vote count is complete, Pennsylvanians can move forward knowing their voices were heard, regardless of whether their vote was counted first or last.”

McCormick thanked Casey in a statement, noting that Casey “dedicated his career to the betterment of our Commonwealth.”

“I am honored to represent every Pennsylvanian in the U.S. Senate, and I will fight for you every day,” he added.

A slight advantage in the race provoked automatic recalculationwhich Secretary of the Commonwealth of Pennsylvania Al Schmidt said on Friday will be stopped after Casey’s concession.

McCormick declared victory earlier this month after The Associated Press called the race for him. Casey, however, remained hopeful because outstanding provisional ballots have been countedeven as Republicans criticized him for waiting to concede.

Casey also took a hit Monday when the Pennsylvania Supreme Court ordered election officials in the state to stop counting mailed ballots are marked with the wrong date or are missing dates on the outer envelopes.

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

McCormick’s victory adds to the majority Republicans gained in the Senate this year, giving them a 53-47 seat advantage in the next Congress. His victory could ease President-elect Donald Trump’s confirmation into the Cabinet.

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