Politics of Pennsylvania

Pennsylvania is generally considered a highly competitive swing state. Throughout its entire history, it voted for the nationwide loser on only 10 occasions (1824, 1884, 1892, 1912, 1916, 1932, 1948, 1968, 2000, and 2004), meaning it has voted for the national winner 83% of the time as of 2024. Although, it generally supported Republicans between the Civil War and New Deal eras, as it voted Republican in every election between 1860 and 1932, except for 1912, when the Republican vote was split. Even then, the state's strong Republican ties meant that it backed Republican-turned-Progressive Theodore Roosevelt. The state backed a Democrat in 1936 for the first time since 1856. Pennsylvania generally leaned Democratic from the 1990s until the 2010s, as it backed the Democratic presidential candidate in every election since 1992 until 2016, when it was won by Republican candidate Donald Trump. After narrowly losing the state in 2020, Trump flipped it back in 2024.

In 2008, Democrat Barack Obama won the state by a margin of over 10 percent, the largest victory seen in a presidential election in Pennsylvania since Richard Nixon's victory in 1972. In 2016, Donald Trump became the first Republican presidential candidate to win Pennsylvania since George H.W. Bush in 1988, winning by a margin of 0.7 percent. In 2020, Democrat Joe Biden defeated Donald Trump in the state by 1.2 percent. In 2024, Donald Trump defeated Kamala Harris by 1.7 percent.

Pennsylvania has a split government as of June 2025, with the governor's office being held by Democrat Josh Shapiro, the state house being controlled by the Democratic Party, and the state senate being controlled by the Republican Party. Republicans control three statewide offices in Pennsylvania: Treasurer, Auditor General, and Attorney General. In the United States Senate, Pennsylvania is represented by Republican Dave McCormick and Democrat John Fetterman. In the United States House of Representatives, Pennsylvania is represented by 10 Republicans and 7 Democrats.

Pennsylvania’s former Senator, Arlen Specter, announced in April 2009 that he was switching his party affiliation from Republican to Democratic, citing the Republicans' shift to the right since he was elected in 1980, though others suspected he switched because he would face a tough Republican primary election in 2010. As it turned out, he ended up losing the Democratic primary to Representative Joe Sestak. Congressman Sestak narrowly lost the general election to Pat Toomey in November 2010, returning the Senate seat to Republicans.