This episode contains strong language. Over the summer, Dave Mitchko started a makeshift pro-Trump sign operation from his garage. By his estimate he has handed out around 26,000 signs, put together with the help of his family. Mr. Mitchko might seem like the kind of voter Joseph R. Biden Jr. wants to peel away from the Republicans in November. He had always been a Democrat — he voted for Barack Obama twice — but opted for Donald Trump in 2016. Today, we speak to voters and politicians on the ground in northeastern Pennsylvania, exploring the factors that swung former Democratic strongholds toward Mr. Trump and asking whether Mr. Biden can win them back.   Guest: Shane Goldmacher, a national political reporter for The New York Times.  For more information on today’s episode, visit nytimes.com/thedaily  Background reading: After the turbulent first presidential debate, Mr. Biden embarked on an old-fashioned train tour to cities where the president won over working-class white ...