“When I hear people say that it is too easy to get on disability, I wonder what system they are talking about,” he said.

Melissa Cooper, 57, began receiving disability benefits shortly after a bullet tore through her spine and paralyzed her while she was sitting in a car outside a store in Memphis, Tenn. For 20 years she could not work as she learned to cope with life as a paraplegic and raise three children with the help of family. Then last year, she earned a bachelor’s degree in English at the University of Mississippi and got a job helping others who are disabled learn to live independently at the Living Independence for Everyone Center in Jackson.

Mr. Trump’s possible vetting of disabled benefits both scares and disturbs her.

“He cannot put himself in my shoes and know the mental trauma associated with me having lost my mobility or how long it took me to get my head back on straight and to want to live,” Ms. Cooper said as she shuffled in her wheelchair and began to cry.

At the East Tennessee Technology Access Center, a nonprofit organization in Knoxville that helps people with disabilities learn to use technologies, there was only anxiety and gloom about the proposed changes.

“I keep thinking of something my grandmother used to say, about throwing the baby out with the bath water,” said Joel Simmons, 55, a counselor at the center who seven years ago had his spinal cord transected in a car accident. “Are we going to just have survival of the fittest?”

Mr. Simmons’s condition is easy to see. But there are others who unquestionably need these meager benefits, he said, but whose disabilities are not as immediately clear.

“Who’s going to decide,” he said of any plan to restrict access. “You’ve got a lot of hidden disabilities. Who’s going to make these decisions? Donald Trump?”