'Never Weakened'

House Minority Leader Nancy Pelosi, a California Democrat, said, "despite the repeated efforts of Republicans to privatize Social Security and end the Medicare guarantee, these vital initiatives remain strong" and "Democrats will always ensure they are strengthened, never weakened."

Presumptive Republican presidential nominee Mitt Romney proposes raising the Social Security retirement age for younger people and indexing benefit increases for higher-income retirees to inflation instead of wages. For Medicare, he endorsed the House Republicans' plan, authored by Ryan.

Some Democrats said the numbers show there is plenty of time to address Social Security's finances. "The program will be fully funded for more than 20 years, so we have time to find smart ways to improve it," said Senate Finance Committee Chairman Max Baucus, a Montana Democrat whose committee has jurisdiction over the program.

The slow economy harms the programs because, when unemployment rises, fewer Americans pay the payroll taxes that support Social Security and Medicare. At the same time, some people unable to find work apply for Social Security benefits earlier than they had planned.

Cost Of Living

Also, the report said, a higher-than-expected 3.6 percent cost-of-living adjustment awarded last year to Social Security beneficiaries helped push up program costs. The trustees said they anticipate beneficiaries will be awarded a 1.8 percent increase later this year.

In addition to Geithner, the trustees are the secretaries of Labor and Health and Human Services, the Social Security administrator and two public representatives.

Social Security has two parts: the old-age and survivors insurance program, which supports senior citizens, and the disability insurance program. Each has a trust fund financed primarily by a payroll tax split between workers and employers. Medicare is funded through a combination of payroll taxes, beneficiaries' premiums and general tax revenue.

Enrollment in the disability insurance program has soared in recent years. There will be 10.9 million beneficiaries this year, according to the report, up 64 percent since 2000.