President Biden plans to reach out to disaffected Black supporters on Monday by taking his campaign to the site of one of the most horrific hate crimes of recent years and decrying the racism and extremism that have shaped U.S. politics. Mr. Biden will fly from Wilmington, Del., where he spent the weekend at his family home, to Charleston, S.C., to address parishioners and other guests at Emanuel African Methodist Episcopal Church, where a white supremacist gunman killed the pastor and eight others in 2015. The visit will be the second part of the president’s two-stage opening campaign swing of...