With more competitive House races than any other state, Pennsylvania’s May 19 primary is shaping up as a high-stakes test of Gov. Josh Shapiro’s (D-PA) political capital as he seeks a second gubernatorial term ahead of a widely expected bid for the 2028 Democratic presidential nomination.

Pennsylvania’s bellwether status in the fight for House control leading up to the Nov. 3 midterm elections runs downstream from its longtime role as a presidential battleground. The Keystone State backed former President Joe Biden in 2020 before flipping to President Donald Trump in 2024, alongside Arizona, Georgia, Michigan, Nevada, and Wisconsin. Voter registration is tight in the state home to more than 13 million people, the nation’s fifth-most populous. There are about 3.8 million registered Democrats to 3.6 million Republicans, making Pennsylvania a microcosm of American politics in the era of Trump.