Glen Campbell with his wife Kim on Capitol Hill Tuesday. (Charles Dharapak/Associated Press)

One way to announce you have Alzheimer’s is to issue a quiet statement and fade into history. That’s not Glen Campbell’s route.

Instead, the “Rhinestone Cowboy” legend publicly announced his diagnosis, sang at the Grammys in February and started a tour of farewell concerts around the world.

Along the way, he’s become an ambassador for the disease: On Tuesday, Campbell turned up at the Rayburn House Office Building for a press conference calling for more government action.

In a corduroy jacket and jeans, the singer seemed to be himself, just older. According to his wife, Kim, Campbell still lights up on stage.

“Music must just be stored in his long-term memory area or something,” she told our colleague Aaron Leitko.

The same must be true of his celebrity schmooze skills. Campbell joked around easily with the room and cozied up alongside his wife to give photographers a better picture. He chuckled politely when Rep. Ed Markey made a labored joke about the cause “needing a rhinestone cowboy.” After his formal remarks, Campbell signed autographs and dutifully scribbled his name into two books and across a vintage promo photo.

Glen Campbell signing autographs on Tuesday. (Charles Dharapak/Associated Press)

But most of the talking was handled by his wife and daughter Ashley who took the podium to spell out the facts of his condition.

“I have to come to the realization that eventually he’s going to look at me and I’m gonna be nothing to him,” she said, tearing up.

For now, Campbell can still play the hits, although sometimes in concert he searches for the right notes.

“You’re nervous because you never know,” said his wife. “You think that one of these days — because this is a progressive illness — you think the other shoe is going to drop and it’s gonna be just devastating when it happens on stage.” Which is why she’s prepared to stop the show at any time. “At a certain stage with this illness, if you want to protect someone’s dignity. I have to respect that and be careful of that.”