The budget hawk group Concord Coalition hailed Ryan's plan to shave $1.6 trillion from projected deficits. But more needs to be done to rein in Medicare costs, the group said in a statement.

"While setting spending targets for federal health care programs provides an incentive for efficiency, and increasing out-of-pocket costs for retirees provides an incentive for economizing, we will still need cost controls, delivery system reforms, and research on best practices to have any chance of reaching those targets," said Concord Coalition Policy Director Josh Gordon in the statement.

Democrats lambasted the Ryan proposal to turn Medicare into a voucher program for those under 55. Republicans "don't believe that senior citizens and people with disabilities have a right to guaranteed health benefits. Instead, they will turn the health of seniors and people with disabilities over to private insurers. Say goodbye to secure health care when you need it most," said Rep. Pete Stark of California, the top Democrat on the Ways and Means health panel.

Social Security

Ryan's plan makes no immediate changes to Social Security but sets up an auto-pilot plan to force Congress to deal with Social Security's long-term financial problems. If Congress does not address the issue, benefits would be cut across the board.

Ryan's plan is likely to gain widespread support among House Republicans. But even if it passes the House, it likely will fail in the Democratic-run Senate and would be vetoed by Obama, AARP's Rother says.

"This proposal is not going anywhere anytime soon," Rother says. But if Republicans win control of the Senate and the White House next year, "that's a whole different story."

Tamara Lytle is a freelance writer and has covered politics and government in Washington for more than 20 years.