Theater lovers, regardless of their political leanings, ought to see “The Cradle Will Rock.” Liberals — or, in today’s jargon, progressives — will like the 1937 musical’s “workers, unite” message. And conservatives can enjoy the Marc Blitzstein pop opera for its history — a period piece that became a classic and which powerfully influenced theater and film, particularly because it brought Orson Welles and John Houseman to prominence.

“Cradle” is on view downtown in a fine production by Stone Soup Theatre, and its portrayal of working-class hardships contrasted with enormous wealth continues to resonate 72 years later, unfortunately much more than it should these days.

Through the years, “Cradle” has inspired considerable controversy, but none more so than at its debut. It was supposed to open as a full-scale production in Broadway’s Maxine Elliott Theatre, which had been leased to the Federal Theatre Project, a New Deal program to help artists. Abruptly, the theater was closed, padlocked and guarded. The ostensible reason was a government budget cut, but most observers believed the shutdown stemmed from accusations that “Cradle” was pro-communism.

Welles, Houseman, and Blitzstein then decided to move to a larger theater, let Blitzstein sit at a piano and read-sing the play, and invite the public in for free. Yet supportive cast members, although forbidden by Actors’ Equity to participate in the production onstage, joined in by speaking the lines and singing their songs from scattered places in the audience. Afterwards, Welles and Houseman, buoyed by the musical’s strong acceptance, formed the successful Mercury Theatre, the troupe that became nationally notorious with its 1938 radio play “The War of the Worlds.”

“Cradle,” as an homage to that beginning, is usually performed with a minimal set and single piano, and Stone Soup’s staging follows that tradition. Director/scenic designer Lindsey Duoos Gearhart has used only a wooden floor, its back section raised to hold the piano and chairs for the cast, and a background wall filled with large and yellowed newspaper clippings headlining bad economic news. Kandice Smalley’s lighting neatly helps the illusion of different locations for different scenes.

Blitzstein was much influenced by Bertolt Brecht, as “Cradle” demonstrates with its political theme, transparent theatrics and obvious names. The story is basic agitprop — workers in Steeltown USA, led by Larry Foreman, battle to unionize but repeatedly get thwarted by the formidable wealth of the company tycoon, Mr. Mister.

There’s no subtlety or nuance, and Blitzstein spares no targets. Mr. Mister literally buys the local press, finances medical research so doctors won’t tell the truth about worker injuries, funds military classes at the university, lavishes gifts on artists, and donates community parks and pools. He spoils his vapid kids, and his wife’s generosity in church collections corrupts the minister. All that’s left to do is pay off Larry Foreman.

Oh, and there’s also police bribery and brutality, war profiteering, deportation threats to immigrant workers, and a woman forced into prostitution by hunger — it’s a litany of society’s ills packed into 90 or so minutes.

The Stone Soup cast is rock-solid (sorry, couldn’t resist), all singing well and many handling multiple roles. Standouts are Bryan Curtiss White, particularly as Rev. Salvation, and Sarah Michelle Cuc, particularly as Mrs. Mister. Katie Harroff, as the hungry hooker, touchingly renders the intro songs in both acts, and Tom Doyle and Anthony Simone harmonize amusingly on “Art for Art’s Sake.” The apt costumes and makeup are by Rocky Deharo.

One quibble: Billy Thompson’s accompanying piano, usually helpful, sometimes drowned out the dialogue.

If you’re unfamiliar with the show and wondering about the title, it’s from the lyrics: “The rich are in a cradle, and when the wind blows, the cradle will rock."

Cast list