NASHVILLE — Tonally, this city’s politics and its most famous export, country music, could not be more different. While the music is full of punched-up emotion and raw tales of wrongdoing, the politics, in recent decades, has tended to be drama-averse, sober-minded and even a bit wonkish.

But not this year. In the prelude to Thursday’s mayoral runoff, the two candidates, David Fox, a former hedge-fund manager, and Megan Barry, an at-large member of the Metropolitan Council, have become embroiled in a heated back-and-forth that feels decidedly partisan, despite the fact that the race is officially nonpartisan.

The mudslinging has caught many residents by surprise in this fast-growing city, where friendliness is regarded as a civic attribute. Mr. Fox has even given it a name: “The Nashville Way.” Which makes it even stranger that Mr. Fox, 54, and Ms. Barry, 51 — who move in the same relatively privileged Nashville social circles — are acting out a kind of real-life version of “You’re the Reason Our Kids Are Ugly,” Loretta Lynn and Conway Twitty’s insult-trading duet from 1978.

“I don’t know what to say about it,” said Jack Cawthon, the owner of Jack Cawthon’s Bar-B-Que, a local chain. “We’re used to staying on the issues, you know.”