MACON, Ga. — President Trump held a rally in Georgia on Friday, 18 days before the November general election. It wasn’t a good sign for him. That Mr. Trump is still campaigning in what should be a safely Republican state — and in others that should be solidly in his column like Iowa and Ohio — is evidence to many Democrats that Joseph R. Biden Jr.’s polling lead in the presidential race is solid and durable. Mr. Trump spent Monday in Arizona, too, a state that was once reliably Republican but where his unpopularity has helped make Mr. Biden competitive....
