Songwriter Daniel Johnston is in critical but stable condition at the Tomball Regional Medical Center, where he's being treated for acute kidney failure, his family said. He has been hospitalized since Nov. 25.

The Whitney Museum of American Art in New York last month selected Johnston, also a visual artist, to participate in the museum's coveted 2006 biennial, and the acclaimed documentary about his life, "The Devil and Daniel Johnston," is one of 15 films short-listed for Oscar consideration and has been picked up by Sony Pictures Classic for release in March.

The Waller-based Johnston, 44, who rose to moderate fame in the 1980s and '90s with his hand-made cassette albums of lo-fi songs, has struggled with manic-depression and bipolar illness for years.

Johnston's father, Bill Johnston, 83, says although there is still no official diagnosis for Daniel Johnston's condition, doctors suspect the kidney failure is from long-term lithium use. Johnston has used lithium for many years to control his bipolar disorder.

"We've ruled out every other possibility we can think of," Bill Johnston said Friday. "We're just waiting to see. He's stable, but that's about all we can say right now."

Daniel Johnston's illness is complicated by what family members describe as borderline diabetes.

In the 1990s, Johnston became an alternative rock icon as various artists covered his songs and cited his influence.

Nirvana singer-guitarist Kurt Cobain was photographed in a Johnston-designed T-shirt.

Johnston released his only major-label album, "Fun," in 1994, the same year that Austin singer Kathy McCarty released "Dead Dog's Eyeball: The Songs of Daniel Johnston."

The design on Cobain's shirt, a frog with the words "Hi, How Are You?" is an image Austinites know from the mural on the side of the corner of Guadalupe and 21st streets.

In late 2003, the image was slated for destruction when Baja Fresh Mexican Grill moved into the space formerly occupied by iconic Austin record store Sound Exchange. But the restaurant said it would keep Johnston's mural after a public outcry.

"The Devil and Daniel Johnston" was shown in March at the Paramount Theatre during South by Southwest, with Johnston in attendance. He also performed at several venues during the festival, including the Austin Music Awards.

Johnston's father said the family hopes to move his son to a hospital in downtown Houston. Johnston does not have medical insurance and is on Medicare, his father said.

Johnston's father adds that no visitation is allowed.

"It wouldn't do anybody any good," Bill Johnston said. "All you can do is look at him."

But Jeff Tartakov, Daniel Johnston's friend, former manager and founder of Stress Records, which distributes Johnston's music on cassette, said he visited Johnston on Sunday.

"I spent an hour with him," Tartakov said. "My girlfriend and I spent the time holding his hand and stroking his hair. It's frustrating that he isn't being allowed visitors."