`Soph': an on-stage visit with the `last of the red-hot mammas' Soph Play by Wendy Westerwelle and Vana O'Brien. Directed by Ric Young.

Think of Sophie Tucker, and your associations probably run to ``the last of the red-hot mammas.'' There's some justice to that. One of America's most popular singers and entertainers during the first half of this century, Sophie Tucker did put across her material with a certain cheerful vulgarity. Her reputation rested in part on what was then regarded as suggestiveness, although all but a few of her songs could be belted out at the average modern church social without raising eyebrows.

Yet a fair synopsis of her long career could omit any hint of ribaldry. The child of immigrant Jewish parents, she struggled from minor-league burlesque to the nation's most prestigious halls by working extremely hard at the entertainment business. She sometimes sang 100 songs a night. She never drank or swore; she was devoted to her mother; she was fabulously generous to both friends and charities; she never forgot a favor. Her talents may have been modest, but she was positively beloved of a wide popu lar following.

That explains all the gray heads in the audience at Portland's Storefront Theatre, a 16-year-old avant-garde theater that usually attracts the young and theatrically au courant. Actress Wendy Westerwelle has all but reincarnated Sophie Tucker. Her one-woman show, ``Soph,'' is both a loving look at the making of a performer and a rousing revival of Tucker's stage act.

Westerwelle has long been one of the most colorful performers in a city with a burgeoning theatrical community. A stoutly built, brazen-voiced actress most identified with broad comedy, she evidently felt a profound kinship with Tucker. She researched Tucker's life for a year and a half before writing the script jointly with Vana O'Brien (another well-known Portland actress). Storefront's artistic director Ric Young directed.

In ``Soph,'' the scene shuttles back and forth between Sophie's backstage dressing table, where she talks directly to the audience about her life and times, and the forestage, where Westerwelle delivers exhilarating excerpts from Sophie's act at different periods during her career. Aside from one slightly talky stretch early in the show, Young has done a most effective job of maintaining dramatic pace despite the episodic nature of the script and the presence of a single performer (aside from accompanis t Ron Snyder).

``Soph'' honestly conveys a good deal of entertainment history. Westerwelle's and O'Brien's script and Young's direction have made it plain enough that Tucker was tough and ambitious, and shown just how tough you had to be to work your way from burlesque to vaudeville to supper clubs to performances before royalty. The show reveals Sophie as a courageous trouper and a sentimental daughter, tearfully warbling ``My Yiddishe Mama'' to her mother. It also shows her getting her start as a ``coon shouter,'' p erforming in blackface when that now-repugnant fad was at its height.

Westerwelle does Tucker's early novelty numbers (such as ``Moving Day in Jungle Town,'' satirizing Teddy Roosevelt's safaris), and the sappy, self-confessional pieces she half-sang, half-talked when her voice was gone but her fans still flocked to see her.

She also tears enthusiastically through several of the ``suggestive'' songs, including ``The Angle-worm Wiggle,'' which got Tucker arrested in Portland, Ore., in 1910, and which is revealed as an innocent bit of merry nonsense.

What is significant isn't the accuracy of Westerwelle's imitation (although older audience members say the resemblance is astonishing). What makes ``Soph'' an electric evening of theater is the authority she brings to Sophie's material. Westerwelle roars unabashedly through Tucker's repertoire with blazing energy and the kind of conviction born of perfect empathy between actress and character. Sophie Tucker may not have been good, exactly, but she was a force, and that comes through.

``Soph'' runs at Storefront until Aug. 31. After a brief hiatus, it then opens at the Westwood Theatre in Los Angeles in late September for an indefinite run.