Why Jessica Chastain found it daunting to sing 'Stand by Your Man' in 'George & Tammy': 'It's such a loaded song'

It's not TV — it's Showtime. And according to Jessica Chastain, her new prestige cable series George & Tammy plays like "a six-hour film" rather than an episodic show.

The 45-year-old actress portrays celebrated country crooner Tammy Wynette in the six-part series, which creator Abe Sylvia and director John Hillcoat adapted from the memoir, The Three of Us: Growing Up With Tammy and George, written by the couple's daughter, Georgette Jon. Chastain has been attached to play Wynette since 2011, and the project was initially announced as a movie, with Josh Brolin playing Wynette's husband and musical collaborator George Jones — now played by her Taking Shelter co-star Michael Shannon.

"There were many years that we were trying to get this off the ground as a film," Chastain tells Yahoo Entertainment at an interview marking the U.K. launch of Paramount, adding that condensing the full arc of Wynette and Jones's turbulent relationship into a two-hour theatrical feature would have been a difficult — and pricey — task. "[We would] not really be able to get into where they came from and why they are the way they are as a film," the actress says. "Also, it would have been expensive, because you have so much music!"

"[We thought] if we could tell this story as a six-hour film, then you're really able to get to know the characters, get to know where their pain comes from and why they have so much difficulty being happy in some sense," Chastain continues. "Nothing about it feels episodic. It feels like the movies they used to make — these four-hour epics. I feel like in the last 20 years, [people have started to say] 'It's gotta be 90 minutes or less.' I really love films that allow me to get to know the things that maybe some executive in some room might not think are very interesting, but for me are the most interesting."

In real life, Jones and Wynette fell in love while touring together in the late ’60s, leading Wynette to leave her husband, Don Chapel, before marrying Jones in 1969. The two stayed together until 1975, ultimately driven apart by Jones's alcoholism and chronic absences. Wynette — who wrestled with her own addiction to painkillers — died in 1998, and Jones followed in 2013.

Although the series is based on their daughter's memoir, both Wynette and Jones wrote their own autobiographies that contain different accounts of their tumultuous relationship. "There are so many competing versions of all of these stories," Shannon acknowledges. "Our scripts are loosely based on Georgette's book ... but then you read George's autobiography, you read Tammy's autobiography and all of the other books that have been written about them and it's hard to figure out which version is the truth."

"They had a lot of ups and downs," Shannon continues. "With George, he would actually be pretty healthy for a while and get his act together and then fall apart again." For Chastain, though, Wynette's slide into addiction more closely resembled “a slow descent into hell." At the same time, she also sees hope in their story. "Even though they end up marrying other people, they're still so connected. It's almost like a spiritual connection that they have. It goes on beyond relationships, it goes on beyond death."

Chastain and Shannon do all of their own singing in George & Tammy, with The Eyes of Tammy Faye Oscar winner belting out one of Wynette's most famous tracks, "Stand by Your Man." That 1968 tune was memorably referenced by Hilary Clinton in a 1992 TV interview about former President Bill Clinton's alleged infidelities. "You know, I’m not sitting here, some little woman standing by my man like Tammy Wynette," Clinton said at the time.

Chastain confesses that she found the prospect of taking on "Stand by Your Man" more daunting than performing any of the songs from Tammy Faye Bakker's back catalogue. "That song is something that you hear over and over again and it's so entrenched in the history of country music," she notes. "Also, the gender debate [around it]. It's such a loaded song that I think most of my nervousness came from that aspect of it."

"I thought it was pretty critical, because a lot of the story of these two people is told through the songs," notes Shannon. "A lot of the emotion and the relationship that they had was from singing together, whether they were married or divorced or married to other people or throughout their life. They came together when they sang and they had a very intimate communication with one another that I don't think we could have accomplished if we were just lip syncing to the music."

Shannon also believes that country music is a crucial part of American culture, with performers like Wynette and Jones serving as avatars for working people through their songs. "Both George and Tammy really are salt of the earth people. They come from very humble, rough origins and they really had to work so hard to achieve the success that they had. A lot of these songs are about love, which is I feel universal. Even though [country music] is a very American idiom, it's also a very universal one."

Given that Chastain now has two Tammy's on her filmography, is she perhaps looking for a third to complete the hat trick? "I think we're gonna just have to create a Tammy — Tammy the Terrible," she says, laughing. "Maybe I could play a character named Tammy the Terrible. I'd see that!"

George & Tammy premieres Dec. 4 on Showtime.

Watch: Jessica Chastain and Michael Shannon attend Paramount+ UK event