President Obama probably never thought he'd be in Massachusetts on Sunday night. But with Republican Scott Brown surging in the polls two days before the special election for Ted Kennedy's senate seat, Obama has scheduled a last-minute trip to Boston to headline a rally for Democrat Martha Coakley. Even before Obama scheduled his trip, however, campaign lawyers in both political parties had begun quietly cramming for the colossal legal battle that could ensue should Brown pull off a stunning upset in one of the nation's bluest states. Republican lawyers fear that if Brown wins, Democrats will use stall tactics to...