At a 1978 rally held after Harvey Milk’s assassination, a group of singers who would become the San Francisco Gay Men’s Chorus gave their first public performance. Their touching tribute to the pioneering gay-rights activist and city councilman helped spark the formation of similar groups across the country, and the gay choral movement was born.

It’s fitting that Milk, who loved opera and theater and has been the subject of many films and books, finally should be feted musically. The hourlong oratorio “I Am Harvey Milk,” written by Broadway composer and performer Andrew Lippa, will be performed this week by the Twin Cities Gay Men’s Chorus (TCGMC), one of six gay choruses that co-commissioned it.

Lippa identifies personally with Milk. Each lived in New York as young men, had an abiding love of theater and was raised Jewish.

“I had my bar mitzvah right before he took office,” he said.

Coincidentally, Lippa’s husband, David Bloch, was a marketing executive at Focus Features when it produced the film “Milk,” starring Sean Penn. But Lippa focused more on historical records to create his own impressions of who Milk was.

The nonlinear work, neither chronological nor strictly biographical, skips around to various significant moments in Milk’s life story. The second movement, “I Am the Bullet,” takes the imaginary point of view of one of the shots that killed him.

“The bullet has no allegiance; it does what it’s told, which is a metaphor for how a lot of people behave,” Lippa said.

The TCGMC will be the third chorus to perform the oratorio, which premiered in 2012 in San Francisco featuring Lippa himself as Milk. For the Minneapolis concerts, the lead role will be sung by chorus member Nathan Croner, with additional solos by Minnesota Opera soprano Elisabeth Comeaux and sixth-grader Quinn Morrissey, a member of the Minnesota Boychoir, as young Harvey. Recent Boychoir graduates also will appear as special guests.

In the first of 12 movements accompanied by chamber orchestra, Milk is a starry-eyed tween who air-conducts Musetta’s Waltz aria from “La Bohème.”

“I laughed at my own audacity writing that,” Lippa said. “How am I going to follow Puccini?”

“Friday Night in the Castro” is an exuberant ode to the San Francisco neighborhood, one of the few places in the country where young 1970s gay men felt at ease, like they belonged.

With lyrics such as “I’ll barrel through” and “Donna Summer in the Trocadero,” Lippa has given the oratorio, a traditional classical form most associated with religious themes, a thoroughly modern pop makeover more in tune with his Tony-nominated work on the Broadway musical “The Addams Family” than Handel’s “Messiah.”

“We talked for a long time about whether to call it an oratorio, which by definition is a large-scale musical work based on a sacred subject,” Lippa said. “As far as I’m concerned it’s appropriate. Let’s reclaim the word and take out the fustiness.”

Message to live authentically

Ben Riggs, TCGMC’s artistic director, said the composition is part of a trend toward commissioning music “that speaks to what our singers identify with and want to sing about.”

Beyond training a spotlight on Milk, the work also uses the classic oratorio crowd scene to comment on what it was like to be gay in 1978, Riggs said: “Its message, like Harvey’s message, is that we owe it to ourselves and our community to live authentically. I forget sometimes that that is still a challenge for some people even now, in 2014.”

In the final movement, “Tired of the Silence,” the chorus sings “Come out” 49 times. The finale also includes the short, powerful sentence from Milk’s famous “hope speech” that became his stump line: “My name is Harvey Milk, and I’m here to recruit you.”

Asked what he most wanted audiences to leave with, Lippa said, “In the Jewish tradition, I’ll answer with a story. After the first of three performances in San Francisco, a young woman, the 21-year-old cousin of one of the singers who had come to see the concert, told him, ‘Guess what I just did? I was so moved I went outside and called my parents and told them I’m gay.’

“I was blown away. You don’t say out loud that you want to write something that inspires people that much, and I don’t know if that happened for more than just her. But it happened for one person.”

To which Milk might have said: “I was here to recruit you. I guess it worked.”