Ballot Initiative 100 doesn't attempt to prohibit all circuses but it would impose a ban in Denver on any circus, carnival or other show that uses exotic animals such as lions and tigers.
Herman contends the animals aren't meant to travel the country caged or in train cars, performing for audiences on cue. Her push to petition for a law ensuring abuse-free circuses rather than just passing out leaflets took some supporters by surprise.
"I guess you get jaded when you get older," said Ashley Soard, formerly of Rocky Mountain Animal Defense and now with Denver for Cruelty-Free Circuses. "Her enthusiasm was contagious."
Herman, a high school sophomore, said she attended circuses as a child but recently became concerned about the treatment of animals. She created a group, Youth Opposed to Animal Acts, started a petition and collected enough signatures to put the question on Tuesday's ballot.
The Ringling Bros. and Barnum & Bailey Circus has been performing in Denver since 1919, and the city's Barnum neighborhood is named after circus founder P.T. Barnum, who bought 760 acres here in 1882 as a winter respite for his show.
The circus has found itself the repeated target of lawsuits and criticism from animal rights groups. The circus' parent company, Feld Entertainment, maintains Herman's initiative would strip the heart of its shows, and that notions of mistreatment of animals are misguided.
"We've certainly been a favorite target of the animal rights crowd," said Tom Albert, vice president of government relations for Feld.
Herman and about 30 to 50 volunteers have raised close to $47,000 from the likes of the U.S. Humane Society and have earned an endorsement from wildlife biologist Jane Goodall.
Yes100.org, the web site set up to promote Herman's ballot initiative, showcases a number of circuses that don't use exotic animals - including Cirque du Soleil and the Big Apple Circus - who would be welcome in the Mile High City.
Feld Entertainment has donated $175,000 to the Keep the Circus in Denver Committee to oppose the referendum. The committee includes City Council members, the Denver Metro Chamber of Commerce and others.
Also agitating on behalf of the circus has been Save the Circus, which calls itself a "volunteer group of circus enthusiasts" whose supporters include the Circus Fans Association of America and Russell Scott - better known in Denver as Blinky the Clown.
"I had no idea it would be this controversial," Herman said from her mother's home, where campaign signs are stacked in the living room. She dropped band last year so she could focus on campaigning.
Herman's proposal would allow educational exhibits like the Denver Zoo and the National Western Stock Show - which showcases livestock and is a locally cherished institution.
Stock show CEO Pat Grant nonetheless opposes the measure, saying the circus is wholesome family entertainment. He said that if the circus goes, the stock show will be next.
"That's crazy," said Herman. "There's a big difference between traveling animals and having a permanent facility. If animals are going to be in captivity, humans should strive to give animals a habitat that's more like their native ones."