HARRISBURG, Pa. (AP) — Democratic US Sen. Bob Casey of Pennsylvania is lobbying for a presidential primary debate to be held in his home state, which is projected as a battleground in the 2020 presidential election. Casey’s letter Monday to Democratic National Committee chairman Tom Perez says holding a primary debate in Pennsylvania would benefit the party in a state that holds great electoral importance to Democrats. President Donald Trump in 2016 became the first Republican to win Pennsylvania since 1988.