The incredibly tight Pennsylvania race between Democratic Sen. Bob Casey and Republican challenger Dave McCormick will head to a recount, Pennsylvania Secretary of the Commonwealth Al Schmidt announced Wednesday.

While provisional and mail ballots are still being counted, unofficial results show the race to be within the one-half of 1% margin to automatically trigger a recount under state law.

Currently, McCormick leads Casey by less than 30,000 votes, an advantage that has shrunk since election night. CNN has not made a projection in the race, although McCormick, a former hedge fund executive who lost a bid for the Senate GOP nomination in 2022, attended new senator orientation in Washington, DC, this week.

CNN has projected that Republicans will win the US Senate majority and retain the House majority, which means that, with control of the White House, the GOP will complete a sweep of the federal government. While the Pennsylvania race is still to be declared, Republicans will have at least 52 seats in the Senate.

Pennsylvania counties will be required to start the recount by November 20. They must complete the recount by November 26 and report results to the state by the next day.

While McCormick claimed victory last week, Casey, a three-term incumbent, has not conceded and told reporters at the US Capitol on Wednesday that there are more votes to count in the race.

“When the vote gets to a certain level, the state makes a determination, they made that determination,” he said. “So, a lot more votes to count.”

CNN previously ranked the Pennsylvania seat as one of the 10 most likely to flip in 2024. While Vice President Kamala Harris lost all seven swing states to President-elect Donald Trump, Democratic Senate candidates narrowly held Wisconsin and Nevada along with open seats in Michigan and Arizona. Meanwhile, the GOP has flipped three Senate seats, toppling Democratic incumbents Jon Tester of Montana and Sherrod Brown of Ohio and winning retiring independent Sen. Joe Manchin’s West Virginia seat.

A victory for McCormick could make Pennsylvania, a pivotal battleground, one of the few states with senators from different parties – for at least four years. Democratic Sen. John Fetterman beat Mehmet Oz, the famed television doctor, in 2022, for his first six-year term.

During the campaign, Democrats tried to paint McCormick as an extremist on abortion and called out McCormick’s trips back to Connecticut (where his school-age daughter lives) and business background. McCormick made an anti-incumbency argument against Casey, calling the senator a “career politician” and asking voters in one of his closing messages to “make a change.”

This story has been updated with additional details.

CNN’s Morgan Rimmer, Simone Pathe and Gregory Krieg contributed to this report.