At the Cooper Tire plant in Findlay, Ohio, Jack Hartley, who is 58, works a 12-hour shift assembling tires: pulling piles of rubber and lining over a drum, cutting the material with a hot knife, lifting the half-finished tire, which weighs 10 to 20 pounds, and throwing it onto a rack.

Mr. Hartley performs these steps nearly 30 times an hour, or 300 times in a shift. “The pain started about the time I was 50,” he said. “Dessert with lunch is ibuprofen. Your knees start going bad, your lower back, your elbows, your shoulders.”

He said he does not think he can last until age 66, when he will be eligible for full Social Security retirement benefits. At 62 or 65, he said, “that’s it.”

After years of debate about how to keep Social Security solvent, the White House has created an 18-member panel to consider changes, including raising the retirement age. Representative John A. Boehner, Republican of Ohio and the House minority leader, has called for raising the age as high as 70 in the next 20 years, and many Democrats have endorsed similar steps, against opposition from some liberal groups. The panel will report by Dec. 1, after the midterm elections.