Merrillville, Indiana. Wayne's World has come to the heartland. Wayne Newton, the Midnight Idol, the King of the Strip, Mr. Las Vegas, with rings to rival Liberace's and poses borrowed from the King, is here, at the Star Plaza Theatre, and more than 3,000 of his fans have come to see him. They're buying Wayne Newton T-shirts. Wayne Newton buttons. Wayne Newton postcards. They're buying it all.

Some of them are seeing him for the third time, some for the 10th. Some, like Karen Peters from Columbus, Ohio, for the 100th. Some of his fans have seen him perform a thousand times."I've seen him five times, every time he's here," says Jean Key of Gary, "and I've never been disappointed. He doesn't just stand up there and sing. He talks to the audience, like he says to the men, `I bet you thought you were going to see Olivia Newton (John).' He's just marvelous."

Newton has been performing for 45 of his 49 years. He has been playing Las Vegas since he was 16, when he dropped out of school to work the lounge in the Fremont Hotel with his brother Jerry; six shows a night, from 5 to 11 p.m.

He was, he says, "an anachronism" - his contemporaries were the Beat-les and the Rolling Stones - and a joke.

"I was the joke of the industry," he says. A big, fat, baby-faced kid singing in a high, girlish voice.

But sometime between 1963, when he recorded "Danke Schoen," and his recent appearance on "L.A. Law," he became a show-biz phenomenon. He figures it happened around 1975. He became the act you have to see when you go to Las Vegas.

Wayne Newton?

Wayne Newton.

Rachel Connell of Grand Rapids, Mich., is the president of his international fan club, and she says nobody thinks she's crazy any more when she tells people she's his fan.

"He's gained credibility," she says, on her way in to catch the show.

Wayne Newton is to Nevada what Don Ho is to Hawaii. There's a street named after him. There's a Wayne Newton Day. His license plate is "Vegas 1." On the marquee of the Hilton Hotel, it says simply, "Wayne." Cab drivers tell you not to miss him. Friends back from junkets say the same. The numbers tell the story.

He can play the 2,200-seat showroom of the Hilton, 36 weeks a year, two shows a night, seven nights a week, and sell it out every time. More than 12 million people have seen him perform live. He's the highest-paid nightclub entertainer in the world.

Each show is two hours long. Newton works without a net: no opening act, no dancing girls, no jugglers. Not even an intermission. Just the band, a couple of backup singers, and Mr. Las Vegas.

"Sammy said to me one night" - no last names are supplied when Newton is talking show biz - "you've got something going that none of the rest of us do. When people go to Vegas, they've got to see two things: Wayne Newton and Boulder Dam."

"Ladies and gentlemen, Waaaaaaaayne Newton!!!!!!!"

Newton, who's part-Cherokee, comes out to an Indian drumbeat and war whoops. He's big, 6 feet 4 inches, with a massive chest, and about 200 perfect white teeth. His hair is black, his tux is tight, his microphone gold. The Don Ameche mustache is gone, but he still looks a little like Zorro. He's wearing a red, white and blue ribbon over his heart, and he opens the show with "America."

"Ya gotta applaud," he says when he finishes. "I'm not just another pretty face." And his Indiana audience - 3,000 strong, a nearly sell-out crowd - does, repeatedly. There are more women in the audience than men, more people over 40 than under. Newton preaches to the converted. He turns around to his band. "This is the crowd we've been waiting for all week."

The "week" began in Milwaukee and is ending in Washington, D.C., with three dates in the 3,400-seat auditorium theater in Merrillville last weekend. Newton is on the road seven weeks a year, flying in his own JetStar. The couch converts into a bed so he can sleep from gig to gig. The band, the crew and the equipment travel in two buses.

"Like a briiiiiidge over Barbara Waaaaaalters . . ."

He stops. "You're not listening. How many of you listen to the lyrics? How many of you don't listen to the lyrics? How many of you don't give a damn? Talk to me. This isn't television."

In response, a long sigh comes out of the audience.

"I hope that was a girl. You ladies, I love you to death - just read the Enquirer. But we men, we're an endangered species. We're the only group that doesn't have anyone out marching for us. Tell me, guys, how many of you thought you were going to see Olivia Newton?"

Newton plays with the audience all night long and keeps the show moving. He does oldies, like "You're Nobody Till Somebody Loves You," and then some rock 'n' roll, pounding the keyboard on "Great Balls of Fire" like Jerry Lee Lewis. He plays a dozen instruments.

When he does his tribute to Elvis Presley - "Are You Lonesome Tonight," "I Can't Help Falling in Love With You" - he not only sounds like Elvis, he looks like him, finishing in profile, in The Pose, head down, one fist raised defiantly.

The first of the evening's four standing ovations comes after "Spanish Eyes." That's the cue for the women, from 30 to 70, to come down the aisles bringing him the roses that were on sale before the show, getting a chaste kiss in return. Nobody is throwing any panties in this crowd, but there's some sedate swooning going on.

"You guys," says Newton. "You bring 'em here, I warm 'em up, and you take 'em home."

He picks out an older couple in the front row. "How long are you two married? Forty-nine years! Oh, my . . . that's a lot of suffering." The audience laughs obligingly. "I don't see any humor in it," says Newton, whose ex-wife appeared on "The Oprah Winfrey Show," part of a panel of kiss-and-tell ex-wives of stars.

"Are you going to do tonight what you did 49 years ago? Do you remember what you did 49 years ago?"

That's about as risque as the show gets. Newton works clean. He lives clean, on his 52-acre estate in Las Vegas, Casa de Shenandoah, where peacocks strut and flamingos frolic, with his father, his daughter, Erin, 15, and his fiance, actress Marla Heasley.

He has never been involved with drugs. He says the drug culture avoided him.

"Drugs have always scared me to death in terms of not being in control. I'm such a perfectionist. And with the schedule that I keep, the discipline that it takes disallows it. I wish I wasn't so disciplined. I see people who seem to have a lot better time than I'm having. There are people who can cast everything aside, and I think, `Wouldn't that be nice?"'