For Clay Aiken (search), performing at what he considers the nation's pre-eminent July Fourth bash, PBS' "A Capitol Fourth" (search) in Washington, could have been moving enough.

But this particular holiday carries deeper significance. His stepfather, Ray Parker (search), 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 ra-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. EDT Sunday on public TV stations (check local listings).

With Barry Bostwick as host, the lineup includesVince Gill (search) and Amy Grant (search); the Bee Gees; gospel singer Yolanda Adams, and the U.S. Drum & Bugle Corps. A 150th birthday salute to "Stars and Stripes Forever" composer John Philip Sousa is planned.

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 his how far he's come in a short time, from unknown to best-selling pop singer (the RCA album "Measure of a Man") (search) 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 (search). This year's winner was Fantasia Barrino, with Diana DeGarmo close behind (DeGarmo's first single, "Dreams," is just out).

Aiken is squeezing the PBS show in between tour rehearsals. In March, he finished a successful series of concerts with the first-year "American Idol" champ Kelly Clarkson (search).

The new 12-state tour, set to kick off next week in North Dakota, includes shows in Wisconsin, Tennessee, his native North Carolina, New York and Delaware.

Aiken labels it a "progression" of his concerts with Clarkson, with "the same band, the same crew, even the same bus driver, believe it or not," but with a new set, different material and video flourishes.

He's added songs connected to "American Idol" that were purged from the previous tour.

It was perhaps selfish, he said, but fans didn't get to hear familiar tunes including "This is the Night" and "Solitaire."

"I wanted to make sure I distanced myself from the show a little bit. Both of us wanted to graduate," he said of Clarkson. "We both wanted to recognize that's where we came from, but at the same time stand alone without the need to have 'American Idol' tacked on.

"When you write this article, I can guarantee you're going to write '"American Idol" alumnus Clay Aiken.' Both of us want to be known as Clay Aiken or Kelly Clarkson," he said.

It might just be a question of time, he concedes.

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."

He and second-season finalist Kimberley Locke, who's become a friend and Aiken's roommate in Los Angeles, were waxing nostalgic over tapes of the show recently.

"Man, I wish I could go back and do that show again," they agreed, according to Aiken. "It was just a lot of fun."

With his contractual obligation to "American Idol" over, he's free to pursue any and all dreams. He wants to cement his musical status ("I'm not really an established recording artist yet") and is intrigued by the idea of returning to television in some way.

And what about long-term goals?

"I'll tell you where I don't want to be: Washed up and still trying to struggle to get people to buy my albums. I want to enjoy this like it's a fun summer camp experience. ... But if at some point it's over, I want to understand it's time to go back to school."