WASHINGTON - In a black lace mini-dress and knee-high boots, Ashley Campbell, the stunning 25-year-old daughter of country music star Glen Campbell, introduced her 75-year-old father to a packed house at the Library of Congress Wednesday night at a concert sponsored by the Alzheimer's Association.

"The first night of the tour, I couldn't get over it," Ashley said. "He got the rowdiest standing ovation when he came onstage. People were so supportive of him. I thought maybe it was just because it was the first night. I had never seen anything like it."

"Until the next night, when it happened again. And the next night, and the next night."

And last night too.  The Washington crowd was on their feet, cheering rowdily, as the familiar, sun-kissed, blond cowboy strode on stage with rhinestones sparkling on his grey suit.

Ashley, who plays the banjo, and two of her siblings are accompanying their father on what is being billed as The Goodbye Tour, which launched last summer after Campbell announced his Alzheimer's diagnosis. On the heels of that announcement came the news of his worldwide tour, a new record and a February performance at the Grammy Awards, where Campbell accepted a Grammy Lifetime Achievement Award.

Campbell offered a heartfelt thank you Wednesday night to the members of Congress in the audience before launching into his famous and now poignant song, "Gentle on My Mind."

"And it's knowing I'm not shackled by forgotten words and bonds," he sang. "That keeps you in the back roads by the rivers of my memory. That keeps you ever gentle on my mind."

Harry Johns, the president and CEO of the Alzheimer's Association, also thanked Campbell for taking his disease to the public and to his fans. Johns said 5.4 million Americans currently live with Alzheimer's disease - 5.2 million aged 65 and older and 200,000 who are under 65. And without a cure, it's only getting worse. By 2050, the association predicts up to 16 million adults will have the disease.

Campbell's disease was evident on stage - prompting a few sad smiles when Campbell asked, joyfully, "Now, who wrote this song?"

"You did," his daughter answered, laughing along with her father.  The audience stood and cheered.

At times, he searched for the right note or the right lyric, but Ashley was ready to jump in at any moment.

Campbell took a break during the concert and twice stopped his band just 15 seconds into a song because it was too loud, hurting his ears. But despite a few misspoken words here and there, the audience sang along with him during the hour-long performance.

In "A Better Place," Campbell sang about confusion, looking directly to his kids on stage. "Some days I'm so confused," Campbell sang. "Lord, my past gets in my way. I need the ones I love, Lord, more and more each day."

"I think music is therapeutic for him," Ashley told the crowd in the middle of the set. "It's what makes him better - it's the best non-medicine medicine."

It was back in the 1960s and 1970s that Campbell earned his fame. After his  time with the Wrecking Crew, the group that played behind famous songs including, "You've Lost That Lovin' Feelin'," "Strangers In the Night" and "Viva Las Vegas," he took off solo. Campbell found success on his own with songs including "Galveston," "Gentle On My Mind," "Wichita Lineman" and "Rhinestone Cowboy," his show-ending song last night - and clearly the crowd favorite.

The Goodbye Tour is slated to continue through July but if last night's standing ovation was any indication, Glen Campbell fans have no intention of saying goodbye to their Rhinestone Cowboy anytime soon.  And the feeling seems to be mutual.