Jeff Daniels in “To Kill a Mockingbird,” which has its official opening night on Broadway on Thursday. (Julieta Cervantes)

As if Jeff Daniels needed any more reminders of the great weight of expectation he has agreed to bear, playing one of the most beloved good guys in all of American letters:

“I was out this summer, and I had a guy come up to me and say, ‘I hear you’re doing Atticus Finch,’ ” Daniels recalls. ‘Yeah,’ I said, and he goes, ‘I taught the book for 35 years.’ ” The man stared gravely at him, the actor adds. “And I said: ‘Well, you’re going to hate the nude scenes.’ ”

Laughter erupts in Daniels’s dressing room in the Shubert Theatre, the fancy-looking little nook until recently occupied by Bette Midler for “Hello, Dolly!” At the moment, Daniels has been joined there by Aaron Sorkin, scribe of “The West Wing” and “The Social Network” and adapter of the highly anticipated new stage version of Harper Lee’s Pulitzer Prize-winning 1960 novel, “To Kill a Mockingbird.”

Daniels and Sorkin, who have worked together before, on the HBO series “The Newsroom” and the 2015 movie “Steve Jobs,” are keenly aware of the special responsibility they’re shouldering. To mount “To Kill a Mockingbird” is to contend with the waves of admiration that generations of readers have stirred up over the novel — a book further immortalized by the 1962 movie version that won Gregory Peck an Oscar. The task of striding out of the shadows of these estimable achievements would perforce require a playwright and a star with firm beliefs that they have something fresh to say.

Theatergoers seem more than willing to give Sorkin and Daniels the benefit of the doubt: “Mockingbird” has racked up advances in double-digit millions of dollars, making it the most sought-after ticket of any new show on Broadway this season.

Daniels likens the role to a mission: “There is such a responsibility playing this part,” he says. “To come through for Aaron, to come through for [producer] Scott [Rudin], when every actor in the world would kill for this. You have a responsibility to go out there eight times a week and hit it.

“And I’m in it for a year. That’s not a 20-week run. . . . The old boys used to do that. [Jason] Robards used to. [Henry] Fonda did this, Brian Dennehy — that’s what the pros do!”

Aaron Sorkin says of his stage adaptation: “I finally woke up and realized that this can’t be an homage; this can’t be an exercise in nostalgia.” (Alexander Koerner/Getty Images)

It was, in fact, the crafting of a stageworthy Atticus with which Sorkin had a particularly strenuous time in the run-up to Broadway, where “To Kill a Mockingbird” has been running for several weeks in previews, in anticipation of its official opening night Thursday. The pressures of adapting the book also were complicated after a lawyer for Lee’s estate filed a lawsuit alleging that Sorkin’s interpretation derogated the “spirit of the novel.” The suit was settled, but the brouhaha underlined the almost sanctified perch that “To Kill a Mockingbird” inhabits in American culture.

The dictates of theater, though, impose structural requirements distinct from a novel’s, a reality Sorkin confronted when Rudin summoned him to New York for a meeting on improvements, after he submitted a first draft. The shortness of their get-together was a sign not that the hard work was over, but that it was just starting.

“Ordinarily, these sessions last three or four days,” Sorkin says. “The session lasted 45 minutes. He gave me two notes.” One of them was that the trial of Tom Robinson — the black man falsely accused of raping a white woman — needed, for dramatic purposes, to start earlier in the play than it does in the novel.

“But the second [note] was the most important,” Sorkin adds, “which was that Atticus can’t be ‘Atticus’ from the beginning of the play to the end,” meaning that if Atticus is the hero, he has to evince some personal growth. “And that’s when I finally woke up and realized that this can’t be an homage; this can’t be an exercise in nostalgia.”

The straight-to-Broadway production, directed by Bartlett Sher, makes Atticus’s defense of Tom, played by Gbenga Akinnagbe, the crux of the evening; the trial is interwoven into both acts of the two-hour 40-minute play. Whereas the novel is told strictly from the point of view of Atticus’s young daughter, Scout, the play parcels out the narration among an adult Scout (Celia Keenan-Bolger), her older brother, Jem (Will Pullen), and their quirky friend from a broken home, Dill (Gideon Glick).

Lee’s beloved characters get their say — especially the housekeeper Calpurnia (played by LaTanya Richardson Jackson) — but Atticus gets the most profound epiphany.

“In the book, Atticus doesn’t qualify as a protagonist,” Sorkin says. “A protagonist has to change. A protagonist has to have a flaw. Atticus in the book, Atticus in the movie, is unflawed.”

Sorkin describes the difference in his Atticus this way: “Instead of Atticus being the guy who has all the answers, in the play he wrestles with the questions.”

Those questions reflect, too, on the inequities of the Jim Crow South of the 1930s that Lee was writing about, in a novel published in 1960 at the dawn of the civil rights movement. The racial cruelties and injustices described through a white child’s eyes don’t readily provide for a 2018 audience a vivid account of how Lee’s black characters think and feel, and that gave Sorkin an opening.

“I was surprised, in going back and reading the book,” he says, “that the only two prominent African American characters had nothing to say about what was the central story in the book. That Calpurnia is more concerned with whether Scout’s wearing a dress or overalls, and that Tom Robinson pleads for his life and that’s all he gets to do. They get to be dignified, but they are basically atmosphere.

“I should add, I don’t fault Harper Lee for any of this: 1960 is different from 2018.”

Jeff Daniels and Gbenga Akinnagbe, who plays Tom Robinson, in “To Kill a Mockingbird.” (Julieta Cervantes)

Thus, the 2018 versions of Tom and Calpurnia achieve a depth of character that previous incarnations did not. Which suits the stage actors just fine.

“This Aaron made very clear from day one,” the Washington-born Akinnagbe says in a phone interview. “The book was amazing, and the movie was amazing, but there were things that were problematic, like minimizing the voices of the black characters. You hardly heard from them.”

The playwright and others on the creative team, Akinnagbe adds, “weren’t interested in continuing that. They wanted to make real people who existed then.”

As a protagonist who channels our outrage over Tom’s treatment by the whites of Maycomb County, Ala., the Atticus that Sorkin and Daniels wanted to conjure had to be flesh and blood, not a monument. And they were helped, they say, by the personal connections both felt to the character.

“You know, my dad was a lot like Atticus,” Daniels says. “Small-town lumberyard guy in Michigan. They’d line up outside his door to talk to him: ‘We’ve got a city council problem — would you . . .?’; ‘Our church needs to raise some money . . . ’ ”

As the actor finishes a story about his father’s enduring friendship with a black resident,Sorkin starts to muse about his past, too.

“I’m just sitting here thinking it’s kind of amazing that Jeff just described his father as being Atticus,” he says. “Jeff’s father — rural Michigan lumberyard owner. My father — a Russian Jewish immigrant living in Brooklyn — and I would describe my father as being Atticus. That says a lot about what Harper Lee did.”

“Decency,” says Daniels. “That’s what she writes about.”

To Kill a Mockingbird, by Aaron Sorkin. Directed by Bartlett Sher. $39-$450. At the Shubert Theatre, 225 W. 44th St., New York. 212-239-6200.