Robert Lopez ranges from ribald ‘Book of Mormon’ to Disney’s ‘Frozen’

For someone who made his name with ribald musical comedies like “The Book of Mormon” and “Avenue Q,” Robert Lopez would have seemed like the last choice on Earth to write the songs for a Disney animated movie. But his work on “Frozen” has been a popular success, earning him his first Academy Award nomination for the song “Let It Go,” which he co-wrote with his wife, Kristen Anderson-Lopez. If they win, Lopez will be able to add the Oscar to the Tony Awards he received in 2011 for co-writing “Mormon” (with “South Park” creators Matt Stone and Trey Parker) and for “Avenue Q” in 2004. “Mormon” is back at the Pantages Theatre in Hollywood through May 11.

It’s hard to believe “The Book of Mormon” is already 3 years old.

I’m really surprised at its staying power. With comedy, the jokes will come out and people will see them coming. Changes in daily life or current events can change the consciousness of audiences and can make the show less funny or feel more stale. The great thing about the show is that it keeps going. It’s as funny now as then. The story has as much power now. We never think about changing it, though obviously with everything you write, you want to make changes.

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There have been rumors about a movie version in the works.

It’s definitely something we want to happen. But it’s not something we’re pursuing.

Given the bawdy nature of your stage work, does it seem odd to you that Disney would pick you to work on an animated movie?

There are two ways to answer that. I kind of approach it from the same place of wanting to be subversive no matter what I’m doing and find the joy in subverting people’s expectations of what they’re going to get. The other way to answer is that I’ve been writing stuff for kids for a long time with my wife — “Winnie the Pooh,” a film that was not paid much attention to; the “Finding Nemo” attraction at Disney’s Animal Kingdom. It’s been a side of myself I’ve wanted to work on, and it’s culminated with “Frozen.”

How exactly did you get the job working on “Frozen”?

They pitched us this story. Whenever Disney asks if you want to do a fairy tale musical, you say yes. I think part of the reason they wanted us was because of her [his wife, Kristen]. She has this great head for story. I think they wanted “Frozen” to benefit from her story talent and our musical instincts.

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How did you collaborate with the screenwriters?

Every day, we would video conference with the story team of “Frozen” and we would discuss the plot — moments, characters — and figure out what we needed to do. It was a grueling year and a half. The release date was coming at us fast. For a while, it looked like we might not pull it off. But in the last three months, the elements came together and it began to feel like a movie.

How many songs did you write for the movie?

In the neighborhood of 30. And we cut 20 of them. We wrote a lot.

What was the process behind writing “Let It Go”?

It took a while to find Elsa’s moment where the song would take off from. At first, she was a spoiled brat and a misunderstood wild child. Then the character changed — she became more secretive, buttoned up, trying to be perfect. … It was hard to get there. But once we got there, it almost wrote itself. Idina [Menzel] has a small voice, but her belt voice is so powerful. The song would be about her going from one part of her voice to that — from quiet, shy, repressed, to Elsa with her powers.

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There are a lot of Broadway actors in the movie. Was that your doing?

I can’t give us the credit for that. Josh Gad [who was in the original Broadway cast of “The Book of Mormon”] was involved before me. It turned out he had a conflict and couldn’t do it when we came on, and that got resolved and then we were able to work together. Broadway actors have a familiarity with this art form and they can really act in the songs in a great way. The one thing we brought in was our friends for the group songs — there are a lot of people from “The Book of Mormon,” “Kinky Boots” and “Avenue Q” in those songs. And I brought Stephen Oremus to do the arrangement and conducting.

david.ng@latimes.com