BOSTON -The leading lady is sidelined with a broken foot that is unlikely to heal in time for the Broadway opening. Her replacement -a talented stage veteran -is getting respectful out-of-town notices but is not generating the kind of star-is-born excitement needed to re-energize the show. The production has been roundly panned. And the box office is in the toilet.

Sounds to me like the kind of musical that closes out of town.

And, in fact, the theater industry is rife with rumors that producers Fran and Barry Weissler are going to pull the plug on their $7.5 million revival of “Sweet Charity,” currently in previews here at the Colonial Theater and scheduled to open in New York at the Hirshfeld on April 21.

There is even talk that the Roundabout Theater’s hit revival of “Twelve Angry Men” will move into the Hirshfeld instead. As of yesterday, however, Barry Weissler was insisting that “Sweet Charity” -the 1966 Bob Fosse musical about a simple-minded prostitute with a heart of gold -would reach New York.

“Of course we’re bringing it in,” he said. “Why would we not? At the end of the day, the public will decide whether we are a success or a failure.”

The backstage saga of “Sweet Charity” is by far the juiciest story on Broadway this spring.

Let’s recap. The leading lady -Christina Applegate -broke her foot during a performance in Chicago two weeks ago. She stepped off a lamppost, heard a crack, hobbled off the stage and was rushed to the hospital.

“Sweet Charity” cast members say Applegate may have injured herself because she was rattled by an incident that happened a few hours before the performance.

She avoided reading her out-of-town reviews (which were not great). That afternoon, she attended a singing rehearsal with the show’s conductor. Laid out on his table were all the notices. Applegate saw them and became “hysterical,” a company member says.

Hours after the accident, Weissler announced that Applegate’s standby, Charlotte d’Amboise, would open the show in Boston and New York. But Applegate has refused to step aside, insisting that, with intensive physical therapy, she’ll be able to dance again by the time the show arrives on Broadway.

That, of course, remains to be seen.

The Weisslers are skeptical, and as one cast member observed, “It’s a dance show. She broke her foot, not her hand.”

D’Amboise is performing the show in Boston right now, but Applegate is there, too. She stands in the wings of the Colonial with her assistant and her dog, studiously taking notes on all the changes being put into the show.

Had D’Amboise opened Wednesday night to glowing notices, Applegate’s days would have been numbered. The Weisslers were prepared to trumpet d’Amboise, who has appeared on Broadway in their hit revival of “Chicago,” as a star whose time has come.

But the Boston critics did not cooperate.

“When d’Amboise is dancing, we see Charity,” wrote Globe critic Louise Kennedy. “When she’s singing, we see an actress who’s working hard to find her way into a new part.” Herald critic Terry Byrne wrote, “Even d’Amboise’s winning charm can’t infuse much life into this ho-hum musical.”

“Charlotte is not getting her due,” Weissler complained yesterday. “She jumped on the court after just three days of practice. It’s a superhuman feat, and she is splendid.”

In her dressing room after the show Wednesday night, a relaxed d’Amboise was taking everything in stride.

“With age, you become realistic,” she said of all the hype surrounding her “Charity” debut. “It’s just great to be doing this role.”

Echoing critics in Minneapolis (where the show started its journey to Broadway) and Chicago, critics in Boston questioned the point of reviving “Sweet Charity.”

A lot of theater insiders are wondering the same thing. A handful of fine Cy Coleman tunes notwithstanding, the show is old-fashioned and second-rate, and was never intended as anything more than a star vehicle for Fosse’s wife, Gwen Verdon.

Asked why he thinks it’s worth reviving, Weissler said, “It’s a coming-of-age story, it deals with the eternal search for love, it’s very funny and it has a classic score. There is human resonance here. I really believe that.

“Apparently, no one agrees with me. What can I say? I thought ‘Seussical’ was good,” he added, referring to his most infamous flop to date.

That one tried out in Boston, too. And there were rumors that Weissler would close it out of town.

He didn’t, and in New York it went on to lose $10 million.