By STEPHEN HOLDEN New York Times Published: July 16, 2010 “This is huge,” Harry Connick Jr. declared on Thursday evening at the Neil Simon Theater, where he made his first Broadway concert appearance in 20 years in a show that runs through July 29. Huge would describe not only the musical forces amassed on the stage — a swing band on one side, a string section on the other and in the center a grand piano that Mr. Connick pounced on with ferocious vigor — but also Mr. Connick’s undiminished determination, at 42, to do it all. Taking control of everything has meant singing, playing, songwriting, arranging, orchestrating and bandleading, all pointed toward the goal of embodying something like a fusion of Frank Sinatra (and Sinatra’s greatest arranger, Nelson Riddle); Elvis Presley; Peter Allen (by way of Professor Longhair); and Frank Loesser reconceived in the spirit of New Orleans. And that ignores his movie career as a sympathetic leading man who can pivot on a dime and play a scary sociopath. The show revealed that (no surprise) Crescent City is, now and forever, the touchstone and wellspring of Mr. Connick’s creativity. The sustained fun began only after the curtain rose for the second act to find him playing a tinny upright piano on a nightclub set. And when the great New Orleans trombonist Lucien Barbarin strolled onto the stage and used a mute that made the instrument growl, jabber, cluck and shout as Mr. Connick played, any anxieties the star might have had about living up to some show business luminaries faded amid the sheer joy of their spontaneous interplay. The two men not only played but also danced, shimmying side by side and cutting up. Joined later by the trumpeter Mark Braud, they made a joyful noise that had the audience stamping and cheering. It was the next-best thing to Mardi Gras, whose party atmosphere was celebrated in several numbers near the end of the show. The first act, in which Mr. Connick sang both standards and originals in a more formal context, suggested a movie going in and out of focus. For his signature song, “It Had to Be You,” he found and held a groove that might be described as a slow bounce and into which he interpolated hot Erroll Garner-like note clusters. With his insinuating voice, which became blatantly seductive the lower he sang, he scored a knockout. In a version of “Hey, There,” from “Pajama Game,” he asserted his power as a roustabout Broadway crooner. “You Don’t Know Me,” from his best pop album, “Only You,” gave the song a defining profile in an arrangement that evoked the sound of an old Brook Benton record. Mr. Connick’s slurred enunciation, pillowy timbre and intuitive phrasing show him to be closer to Presley in his vocal sound than to Sinatra. Rhythmically, however, he remains a Sinatra acolyte. The Ol’ Blues Eyes he conjures (adding some of Dick Haymes’s moist heat) is the aggressive later edition, who liked to punch up the rhythm with staccato exclamations. Especially as an arranger, Mr. Connick favors broad musical strokes — sudden roaring fanfares and blasts of noise — over more refined gestures. More often than not, the instrumental choirs call and respond rather than blend. Strings are conventionally used in pop as a textural ingredient to deepen a mood and to add color. During much of his concert, they were deployed like the brass and horns, often making for a sound that was murky, cluttered and expressively undefined. Mr. Connick’s rough-hewn, swing-driven aesthetic is ultimately grounded in New Orleans ragtime, blues and boogie-woogie traditions. He may go to Las Vegas, Hollywood and Broadway, but he is finally a proud native son. “Harry Connick Jr.: In Concert on Broadway” continues through July 29 at the Neil Simon Theater, 250 West 52nd Street, Manhattan; (212) 757-8646, ticketmaster.com.