Philadelphia has approved four demonstration permits in support of Sen. Bernie Sanders at the July Democratic National Convention — including a large rally planned near the convention’s epicenter. One of the permits is for an event consisting of four days of all-day rallies at FDR Park in support of Mr. Sanders. The city said it expects 30,000 participants, and organizers said in an interview they hope turnout will be much higher. The park is adjacent to the Wells Fargo Center, where many of the Democratic National Convention events will be held — raising the possibility of a large demonstration in...