HARRISBURG (AP) — Pennsylvania’s U.S. Senate race between three-term Democratic Sen. Bob Casey and Republican challenger David McCormick could help Republicans pad their newfound majority in the chamber in a battleground state contest that is one of the nation’s most expensive this year.

McCormick led vote counting early Wednesday morning by about 100,000 votes, or 2%, but a significant number of votes remained uncounted.

At Casey’s election night party at a hotel in his hometown of Scranton, Mayor Paige Cognetti, a Casey ally, expressed confidence that Casey would ultimately win once all votes were counted. But, she told partygoers just before midnight to go home in hopes that a result would become clear on Wednesday.

Casey, perhaps Pennsylvania’s best-known politician and the son of a former two-term governor, is seeking a fourth term after facing what he has called his toughest reelection challenge yet. Casey, 64, is a stalwart of the state’s Democratic Party, having won six statewide elections going back to 1996, including serving as the state’s auditor general and treasurer.

McCormick, 59, is making his second run for the Senate after losing narrowly to Dr. Mehmet Oz in 2022’s Republican primary. He left his job as CEO of the world’s largest hedge fund to run after serving at the highest levels of former President George W. Bush’s administration and sitting on Trump’s Defense Advisory Board.

The race ran on national themes, from abortion rights to inflation. But it also turned on local ones, too, such as Casey’s accusation that McCormick is a rich carpetbagger from Connecticut’s ritzy “ Gold Coast ” — a caricature McCormick helped bring to life by mispronouncing the name of one of Pennsylvania’s local beers — trying to buy Pennsylvania’s Senate seat.

Casey also attacked McCormick’s hedge fund days, accusing him of getting rich at America’s expense by investing in Chinese companies that make fentanyl and built Beijing’s military.

McCormick, in turn, stressed his seventh-generation roots in Pennsylvania, talked up his high school days wrestling in towns across northern Pennsylvania — a sport that took him to the U.S. military academy at West Point — and his time running online auction house FreeMarkets Inc., which had its name on a skyscraper in Pittsburgh during the tech boom.

Casey, a staunch ally of labor unions and President Joe Biden, has campaigned on preserving the middle class, abortion rights, labor rights and voting rights, calling McCormick and former President Donald Trump a threat to all those.

McCormick, in turn, accused Casey of rubber-stamping Biden administration policies on the border, the economy, energy and national security that he blames for inflation, domestic turmoil and war.