NEW YORK CITY — At a recent performance of Chicago at the Ambassador Theater on West 49th Street, a rumble of anticipation preceded Jinkx Monsoon’s entrance on stage.

The two-time RuPaul’s Drag Race winner and frequent Provincetown stage presence is playing Matron “Mama” Morton in the long-running musical, a showy supporting role that’s previously been performed by Jennifer Holliday and Patti LaBelle. This is the first time the role has been played by a drag performer on Broadway.

In a fitted black suit, her signature red hair molded in Jazz Age style, Monsoon entered from the wings brimming with confidence, appearing every inch a Broadway star. As she launched into her showstopping number “When You’re Good to Mama,” her perfectly clear and powerful belt quickly dispelled any doubts over whether she could hold her own with the show’s veteran ensemble.

“I think working my way up from dive bars to cabaret spaces to big theaters taught me how to maintain an intimate connection with my audiences, even while the venues changed,” Monsoon said between shows.

The musical was originally a vehicle for Gwen Verdon, who spent years trying to get the rights to the story. It would eventually be directed and choreographed by her estranged husband, Bob Fosse. Verdon played the starring role of Roxie Hart opposite Chita Rivera’s Velma Kelly, a supporting role that was expanded in rehearsals. (The recent FX limited series Fosse/Verdon dramatized the creation of the show and Verdon’s intense determination to make it a hit.) Broadway hitmakers Fred Ebb and John Kander wrote its now-classic score. With a stage overflowing with the talents of the best of the best, Chicago seemed ready to launch itself in the stratosphere of all-time Broadway successes when it premiered in 1975.

But the musical’s story of celebrity status acquired by behaving badly — and without a shred of remorse for the crimes committed along the way — bothered some critics and audiences. The show received mixed reviews, and although it was nominated for 10 Tony Awards, it was swamped by the tsunami of A Chorus Line. It ran for 936 performances on Broadway, a respectable but modest hit.

The 1996 revival, however, is already the longest-running American musical. (When Phantom of the Opera closes this April, Chicago will become the longest-running musical — period.) It’s spawned endless productions that have toured all over the world, and the 2002 film version starring Renée Zellweger and Catherine Zeta-Jones won the Academy Award for Best Picture.

But even the revival has had its share of detractors. There’s always been a low-grade grumble in the Broadway community from those who take issue with the frequent casting of television celebrities — many without any previous stage experience, like Pamela Anderson and Wendy Williams. (Others point out with gratitude that the show has employed thousands of actors and theatrical workers for nearly three decades, and those offbeat celebrity castings have been a hit with audiences.)

There’s a moment in the first act when Roxie Hart, awaiting trial for murdering her lover, confesses to the audience that she is “older than she ever intended to be.” Likewise, I must confess that I have seen more live versions of Chicago than I ever intended to see, including the first national tour in 1978, the original cast of this revival when it debuted in 1996, a production in Vegas starring Chita Rivera, and a German-language production in Berlin. (Note: I don’t understand German.) Perhaps most alarmingly, I’ve also seen it at sea.

So, I feel confident telling you that the current cast is terrific. Everyone on that stage is bringing their best. But the true test of any production of Chicago is the strength of its two leading ladies, Roxie Hart and Velma Kelly, and Charlotte d’Amboise and Amra-Faye Wright are impeccable in those roles. Both actors have been performing the parts for more than 20 years, yet each manages the astonishing trick of conveying total presence and commitment. Their roles demand extraordinary physical resilience. How is it possible to pull that off?

“Doing eight shows a week isn’t easy,” said d’Amboise, who first played Roxie in 1997 and has performed in the show at some point every year since 2001. (She notably played the role in 2005 while simultaneously standing by for Christina Applegate in Sweet Charity.) Although the two-time Tony nominee isn’t a household name outside of Broadway, within the community she is a beloved figure. Any performance she gives is exalted.

“It’s a constant battle to keep Roxie alive and spontaneous,” said d’Amboise. “Falling in love with your character and trying to stay in the moment is how I stay focused and continue to grow. It helps when I have the fabulous Amra-Faye to work off, and of course that glorious score and book.”

South African artist Amra-Faye Wright — the first actor to play Velma in both English and Japanese — shares her co-star’s strategy for keeping the role fresh. “Maintaining consistent focus comes from a strong desire to give the audience the best possible experience,” she said. “Unless you’re focused, you can’t possibly react honestly to whatever your fellow actors are serving up, and that would just be boring.”

And Monsoon, who is playing “Mama” through March 12, is focused on performing with the same self-discipline as her co-stars. She said she’s trying take away as many lessons as she can from the experience.

“Stamina, self-preservation, and forgiving yourself for not being perfect all the time” are some of those lessons, she said. “I’ve put in my years performing, touring, and tromping the boards. But nothing quite prepared me for eight-show weeks in the dead of winter in New York City. I’ve learned so much in such a short amount of time. It’s incredible!”

Is Monsoon looking ahead to possibly reprising this role should the show continue for another 30 years? (Because it very well might.)

“I’m trying not to plan too far ahead right now,” she said. “I’m extremely proud to be where I’m at, and I know there’s more right around the corner. I just really want to live in this moment, which is fantastic beyond words.”