After Tuesday night's American Idol, the arguments will begin:

Are Clay Aiken or Ruben Studdard better singers than Justin Guarini?

Will Julia DeMato, Vanessa Olivarez or Kimberly Caldwell make people forget about Kelly Clarkson, last year's winner?

Is this American Idol better than last year's?

From a TV perspective, that last question is a no-brainer: This American Idol not only is better than last summer's show - it's the most powerful show on prime-time television.

What was just a summer sensation against reruns last year has exploded into a phenomenon, drawing 44 million viewers each week.

The 12 finalists on American Idol (clockwise from left): Trenyce, Joshua Gracin, Clay Aiken, Kimberly Caldwell, Ruben Studdard, Kimberly Locke, Charles Grigsby, Carmen Rasmusen, Rickey Smith, Vanessa Olivarez, Julia DeMato and Corey Clark. Fox

Fox's Wednesday Idol (8:30 p.m. today, Channels 19, 45), in which winners are revealed, ranks No. 4 this season behind CSI: Crime Scene Investigation, Friends and Joe Millionaire. Tuesday's telecast, which lets viewers vote for their favorite singer, ranks No. 6, following Survivor: The Amazon.

But it's not just the ratings for Fox's twin towers that are the envy of other networks. Unlike any other show on TV - scripted or unscripted - American Idol has proven to be an extraordinarily expandable franchise. American Idol episodes seem to multiply like rabbits, while producer Mark Burnett has never figured a way to stretch out CBS' popular Survivor franchise.

First Fox padded the front end of American Idol by devoting 5 1/2 hours to auditions in January, before February's sweeps ratings period started.

In the middle of February, Fox threw in American Idol: The Best of the Worst, new and old clips from its videotape stash.

Two weeks ago, Fox threw out the rules and added four wild-card singers - not two - inflating the final field to 12.

"When they did the `Best of the Worst,' the judges saw some singers that they really liked, and each one wanted to chose a finalist," explains Jason Clark, show publicist.

To make room for two additional performers, the Tuesday shows this week and next were doubled to two hours - giving Fox more

unique, original programming against March reruns.

And by adding two finalists to the weekly elimination contest, Fox must add two weeks - or four more shows - to this season. So American Idol likely will conclude May 20-21, the final two days of May sweeps, instead of the previously announced May 6-7.

Four more top-rated American Idol broadcasts in May could ensure Fox a victory this season in the 18-49 demographic desired by advertisers.

Fox Entertainment president Gail Berman credits the success to her expanding man, Mike Darnell, the executive in charge of Fox's alternative and reality series.

Payoffs all around

"Mike is one of the great network executives," she says. "We think he's the best in the business at what he does." (They didn't say that after Fox aired his Who Wants to Marry a Multi-Millionaire, the Darva Conger-Rick Rockwell fiasco three years ago.)

Berman also remembers how ABC burned out its reality gem, Who Wants to Be a Millionaire. So she's not planning two Idols a year, to match CBS' Survivor.

"We believe that American Idol is a once-a-year program. It is not our intention to put it on in the fall," she says.

Fox programmers adore Idol not just because it's making a ton of money. The singers have blown away competitors' lineups, while boosting ratings for Fox's 24 and Boston Public.

The West Wing ratings have fallen from the one-two punch of ABC's The Bachelor/Bachelorette and biggie-sized Wednesday Idols.

NBC has thrown a low-budget Let's Make A Deal revival this month against Idol at 8 p.m. Tuesday just to keep the lights on. "It's been incredibly hard to find some show to work (at 8 p.m. Tuesday)," admits Jeff Zucker, NBC Entertainment president.

Two-hour Tuesday Idols - which pre-empt 24 - also help stretch the 24 episodes of Kiefer Sutherland's thriller into May without repeats.

And in the shrewdest twist, Fox has given American Idol fans a reason to watch Monday's Boston Public high school drama. Singer Tamyra Gray from last summer's Idol joined the show Feb. 24 for seven episodes as Aisha, being mentored by music teacher Marylin Sudor (Sharon Leal). Now that's a crossover artist.

How to steal the idea

Other networks are scrambling to cash in on Idol. CBS has revived Star Search, while USA launched a country music talent competition called Nashville Star last Saturday. ABC premieres All-American Girl today (9 p.m., Channels 9, 2), joining the Are You Hot? competition.

The Search for the Most Talented Kid in America debuts on NBC March 21 (8 p.m., Channels 5, 22), soon to be followed by NBC's competition for senior citizens, standup comics and movie action stars. And WB plans a live summer music show, Live From Right Now, from Michael Davies (Who Wants to be a Millionaire).

As humorist Fred Allen once said, "Imitation is the most sincerest form of television."

But we'll always remember the original, not the knock-offs. And American Idol has set the gold standard for TV talent shows. Which is why, years from now, we'll still be arguing about which American Idol cast was the best, as we do with Survivor or The Real World.

We won't remember who won Are You Hot?, I'm A Celebrity - Get Me Out of Here! or Celebrity Mole.

E-mail jkiesewetter@enquirer.com