by Peter Bowes in Los Angeles

Clay Aiken and Ruben Studdard are the two finalists

US TV viewers will vote for their second American Idol winner tonight.

The show has developed a phenomenal following since the first series catapulted Kelly Clarkson to stardom.

Clay Aiken, a geeky crooner with a big, rich voice, appears to have a slight edge to take the title.

His rival is Ruben Studdard, a gentle giant of a guy with a flare for R&B and gospel music.

"Ruben is the industry's favourite, Clay is the American phone-in favourite," said record label executive John Rotella.

"Clay has more of a presence for stage, like Broadway," added Janice Leverett, an entertainment industry lawyer.

"Ruben has a radio friendly voice."

Most people agree that the final will be very close, with both contestants enjoying a loyal following. The winner will be announced on Wednesday night.

Seacrest has had to pad out the show on some occasions

Leaving aside the apparent exuberance of the show's fans, the second series of American Idol has not encountered such overwhelming enthusiasm from the music industry.

There is a sense that the show is cashing in on its success to the point of producing dreary television.

The results edition - screened in the US the night after the contestants perform - has been extended to one hour.

The drawn out process of announcing that week's winner is padded out with recaps and cheesy features about the would-be idols. The host, Ryan Seacrest, has even commented on-air that he is being asked to fill for time.

"They were just straining to fill an hour of programming - it really could have been done in a half hour," said Mr Rotella, of Shout! Factory, a new record label distributed by Sony.

Seacrest has made something of a catch phrase out of getting the audience to hang on until "after the break".

Country-style singer and US marine Josh Gracin made the final four

"It's just not that interesting to wait," said Mr Rotella.

"They milk it for all it's worth - but who can blame them?" added Ceci Vasconcellos, who works for the Recording Industry Association of America - an umbrella organisation representing all the major record labels.

The series was on air throughout the period of the war with Iraq. One of the contestants, Joshua Gracin, a fairly average country singer, made much of his real job a US Marine.

To the surprise of many - and the frustration of Simon Cowell - Josh survived in the contest until the final four.

"I think that because we were in war we felt almost obligated to keep him there a little bit longer than he should have been" said Ms Leverett.

Also taking a cue from the war, the series spawned the charity single, God Bless the USA. Some of the proceeds go to the American Red Cross.

Scott Pansky, an entertainment industry publicist and "raving fan" of American Idol, said such "cause-related marketing" was a unique aspect of the show since it gave fans a chance to support the victims of the war.

Robin Gibb joined the judging panel for one show

A new feature of the show was the inclusion of celebrity judges, and an impressive list of veteran performers took a seat with the regular panel of Simon Cowell, Paula Abdul and Randy Jackson.

They included Robin Gibb, Neil Sedaka and Smokey Robinson.

But the choice of star judges reflected the musical choices of the contestants. There has been some criticism that on several occasions they were asked to perform songs that are out of touch with today's chart material.

"There's got to be a better way of getting these guys to sing hip or current tracks or recent songs that just have an edge," said Mr Rotella.

But others found the musical direction of the show to be inspiring.

"Instead of finding the next Britney Spears, what they are potentially finding is the next Barry White or the next Barry Manilow of our generation,' said Mr Pansky.

Kelly Clarkson was the winner of the first series

"They've actually created a new kind of idol."

Kelly Clarkson's first single, A Moment Like This, became an instant hit and a radio play favourite.

"The nice thing about it is that it has sort of allayed the whole perception that there's one caucus that decides the 10 songs that are just going to get played everywhere over and over," said Angie Diehl-Jacobs, from Clear Channel, which owns more than 1,200 radio station around the US.

"This empowers the public to a greater degree - they feel like they are actually having a say in it," she said.

But Marvin Etzioni, a singer songwriter and record producer, described the show and its young stars as "American culture at its worst."

"I think it's going to be short-lived. It's the Joe Millionaire of pop music. It just feels really empty and hollow," he said.

"American Idol promotes generic, faceless, shallow singers who have not found any original voice. Few, if any of these future 'celebrities' will have any lasting impact."