Democrats count the votes in Chicago, so Republican candidates often don't even run for mayor. Some years back, the D's wanted "an investigation" of the GOP for not running a candidate for mayor in Chicago - they were upset that the GOP put ALL their Illinois campaign money into places where they could - and sometimes did - actually win. The D's got the bright idea of making the GOP waste money in rigged Chicago races instead, but they couldn't actually come up with a way to force that.