2024 United States Senate election in Pennsylvania

The 2024 United States Senate election in Pennsylvania was held on November 5, 2024, to elect a member of the United States Senate to represent the state of Pennsylvania. Republican businessman Dave McCormick won his first term in office, defeating Democratic three-term incumbent Bob Casey Jr. in what was considered a major upset. Most predictions gave Casey a slight advantage, and he led in most polls. Along with Sherrod Brown in Ohio and Jon Tester in Montana, Casey was one of three incumbent senators to lose re-election in 2024, all of whom were Democrats first elected in 2006. The primary election took place on April 23, 2024. The election was considered essential for Democrats' chances to retain their majority in 2024. The Associated Press and Fox News declared McCormick the winner on November 7, while Decision Desk HQ called the race for McCormick on November 14. CNN, NBC, ABC, and CBS all called the race for McCormick on November 21; Casey conceded the race later that day, halted a recount and confirmed the result. This was Pennsylvania's closest US Senate election since the passage of the Seventeenth Amendment, as well as the closest Senate election of the 2024 cycle. McCormick was the only Republican challenger to win in a state flipped by Trump in the 2024 presidential election. The other three Republican Senate gains were in states Trump had won in all three of his runs. With Democrats flipping the other Senate seat two years earlier, this was the first time since the 2012 Senate election in Indiana where the opposite party flipped a seat after losing one in the previous cycle. Notably, the margin of just 0 % between the Republican and Democratic candidates is fewer than the votes received by either the Libertarian candidate, John Thomas (1 % of the vote), the Green candidate, Leila Hazou (0 % of the vote), or the Constitution candidate, Marty Selker (0 % of the vote). This was Casey's first general election loss of his political career, and the second counting Casey's primary election loss in 2002. This election made Pennsylvania one of several states to have a younger senior senator (John Fetterman) and an older junior senator (McCormick). McCormick was sworn in on January 3, 2025.