PHILADELPHIA — Campaigning on crime and looking for boogeymen, Republicans in Pennsylvania have zeroed in on Philadelphia's progressive district attorney, a national leader on criminal justice reform who could be impeached just ahead of the November election. The drive against Larry Krasner has already divided Democrats on the politically charged issues of policing and public safety, cleaving at the diverse coalition of voters Democrats need to turn out in this critical swing state. “All we need to do is keep together the Democratic coalition that elected Joe Biden,” said Joe Corrigan, a Philadelphia-based Democratic strategist involved in several local and...