The ‘Rat Pack’ swings in the new year

Though his velvety voice and legato phrasing are spot on, Chris Jason says he’s not a Frank Sinatra impersonator.

“I don’t put myself out there as one,” says the singer, who plays the legendary crooner in the Las Vegas tribute “The Rat Pack Is Back!” at the Patchogue Theatre for the Performing Arts Saturday through Monday. Playing gigs as the Chairman of the Board since he was a young teenager, Jason says, “I last because of the vocals.”

Growing up in Rhode Island’s Little Italy neighborhood of Federal Hill, Jason says he enjoyed a good giggle from his pals after belting out a karaoke “Luck Be a Lady.” But when he joined his uncle — an Engelbert Humperdinck tribute artist — onstage at age 14, Jason knew he’d found the role of a lifetime.

After performing as “Ol’ Blue Eyes” for nearly two decades on the East Coast, he finally made it to the Strip last year, as a resident entertainer in the Vegas throwback to the ring-a-ding-ding times when Sinatra and his Hollywood cronies lit up the Sands Hotel’s legendary Copa Room.

Long before Taylor Swift had her circle of A-list BFFs, Sinatra had his celebrity squad. Johnny Edwards says he jumped at the chance to play fellow Rat Packer Dean Martin when approached by Dick Feeney, the Vegas show’s producer, in 2004, after an 11-year run as Elvis.

“I always enjoyed Dean not only as a singer but as a true showman who was the true King of Cool,” Edwards says. His ever fun-loving and at-ease persona made him a perfect fit for me.”

After Jason opens with a crowd-pleasing Sinatra standard or two, Edwards as Dino and Kenny Jones, who plays Sammy Davis Jr., ascend from the audience onto the stage, recalling the impromptu appearances of the storied entertainers in each other’s nightclub acts. “Dean Martin, maybe Frank, maybe Sammy” read the Sands Hotel’s marquee.

Rat Pack foolery ensues, with the high-rolling celebs trading wisecracks and one-liners and putting down their highballs to deliver a Yuletide classic or a medley of signature hits. “There is a blueprint,” concedes Jason. “Eighty percent is scripted, but the rest is off the cuff.” The ad-lib bantering often includes audience members, who also get the chance to join in singalongs.

Still, theatergoers may suspect the cast is having more fun than the crowd they’re entertaining. Just like the original Rat Pack, Jason, Edwards and Jones would say they were right.