July 3, 2004 -- FOR Clay Aiken, performing at what he considers the nation's pre-eminent July Fourth bash, PBS' "A Capitol Fourth" in Washington, could have been moving enough.
But this particular holiday carries deeper significance. His stepfather, Ray Parker, a veteran, died two years ago on July 4. His younger brother, 18-year-old Brett, just enlisted in the Marines.

"This Fourth of July is special because my dad was in the Air Force and my brother is now in the military," said Aiken. "It gives a little more meaning to it this year."

Aiken, the formerly gawky redhead whose powerful voice gained him "American Idol" fame, plans to sing the national anthem; Lee Greenwood's "God Bless the USA" and an orchestra-backed version of "Measure of a Man," from Aiken's album.

He's in good company at the ceremony, which airs live from the West Lawn of the U.S. Capitol 8-9:30 p.m. tomorrow on PBS (8 p.m./Ch. 13, 9:30 p.m./Ch. 21).

With Barry Bostwick as host, the lineup includes Vince Gill and Amy Grant; the Bee Gees; gospel singer Yolanda Adams, and the U.S. Drum & Bugle Corps.

Rousing patriotism is one thing for Aiken, politics quite another.

"Music gives people the opportunity to come together and all enjoy one thing and politics, as important as they are to the success of the country, do more to divide, unfortunately. I don't want to be part of that," he said.

About a half-million people attend the annual PBS concert a prospect Aiken doesn't find daunting.

"I'm more excited about it, actually. I was invited to a different Fourth of July event but I wanted to do this one . . . It's just a cooler opportunity to be in Washington, D.C., for the holiday, with a big 110-piece orchestra."

How does the 25-year-old pop star come by such poise?

"I might be a little less self-possessed than comes across," he said, with cheerful candor. "I just do my best to portray it, to make sure I don't look nervous."

Besides, he remains aware of how far he's come in a short time, from unknown to best-selling pop singer (the RCA album "Measure of a Man") preparing for his first solo concert tour.

"I try to remember it was just barely a year ago that I was sitting in North Carolina not doing much but teaching and going to class and turning my homework in late," he said. "And it could very easily come back to that at any moment, so I try to remember that as much as I can."

A one-time YMCA camp counselor who majored in special education, Aiken was the second-season runner-up to soulman Ruben Studdard. This year's winner was Fantasia Barrino, with Diana DeGarmo close behind (DeGarmo's first single, "Dreams," is just out).

He and other "American Idol" contestants are fond of the obscure fact that Gladys Knight was discovered on "Ted Mack's Amateur Hour."

"I would love to have that kind of history," Aiken said, but diplomatically adds: "I don't want to abandon that part of me because I wouldn't be here if not for that show." Post Wire Services