Some lawmakers, including Sanders and DeFazio, want Social Security spared from changes, such as raising the retirement age, when the commission on which Simpson serves makes its recommendations.

Differences over the future of Social Security likely will fuel debate about Simpson's "rant," said Robert L. Bixby, executive director of the nonpartisan Concord Coalition, which has called on Congress to curb the immediate deficit and prepare to pay for the retirement costs of the baby boomers.

"That's why the furor might not die down," Bixby said. "There is the whole issue of whether Social Security ought to be on the table."