Pennsylvania emerges as ‘tipping-point’ battleground for Biden and Trump — before and after Election Day

Both parties are increasingly focused on the pivotal — and potentially messy — role that Pennsylvania could play in deciding the outcome of the presidential race.

President Trump’s campaign in recent days has redirected ad spending there from other northern battlegrounds, while Joe Biden’s campaign and supportive groups are increasing their spending in the state, which between its rolling rural expanses and major metropolitan hubs is seen as a classic political bellwether.

Both sides now see Pennsylvania, with 20 electoral college votes, as a must-win prize on the path to...