Then the Chicago Democratic Machine would "find" more votes for the person in the 'sure' seat.

Oh, wait! This is your election we're talking about. :)

(After the last census, I was gerrymandered from a safe Republican district to a safe Democratic district. The old Republican district is now a block away from my home and somewhat less safe than it was. Of course, it's still worth voting in other races, but U.S. House is a joke.)