Mayor Francis Slay may not even live in the 23rd Ward anymore, but the crowded fight for his old aldermanic post there should help his chances of re-election next year.

So far, a quartet of hopefuls have signed up to run in the Democratic primary for the ward’s alderman: Car wash owner Joe Vaccaro, Lindenwood Park’s Colleen Bridges, a community college instructor, public health analyst Mary E. Homan, and Judi Roman, a veteran Democratic operative.

The incumbent, Kathleen Hanrahan, has signaled she would not seek re-election.

So how does that help Slay?

As the St. Louis American suggests this week, a lively contest ensures that a key part of Slay’s base comes out to vote on March 3 — the same day he’ll be seeking his nod for a third term.

For those who doubt such peripheral races matter in citywide contests, just ask Lewis Reed, whose underdog bid for aldermanic president last year was buyoed by a race in his home ward. His opponent, Jim Shrewsbury, had more money, but no compelling local match-ups to help motivate supporters to get to the polls.

Slay represented the 23rd Ward, a leafy south St. Louis enclave that also includes chunks of the Ellendale and Clifton Heights neighborhoods, from 1985 to 1995.

His father, Francis R. Slay, has been committeeman there for many years, and will likely have considerable say over who represents the area at City Hall.

The mayor, though, will have to watch from afar. This summer, he and wife Kim moved to a home a few miles south near Carondelet Park — which is in the 12th Ward.