While many people worry about the billions of dollars spent bailing out banks, auto makers and other sectors, looming shortfalls in Medicare and Social Security are what could ultimately sink efforts to revive the sagging U.S. economy.

As 78 million baby boomers begin to retire, funding for the government's two primary old-age security plans grows increasingly precarious -- even as the equity collapse that has taken a toll on private retirement savings and employment is creating additional drag on the nation's two major entitlement programs.

A report released earlier this week by trustees of the Social Security and Medicare trust funds shows that Medicare payments are expected to surpass the program's surplus in 2017, two years earlier than projected last year. The surplus in the Social Security trust fund is now forecast to run out in 2037, four years ahead of last year's estimates.

According to Kent Smetters, a Wharton insurance and risk management professor, shortfalls in Medicare and Social Security total between $80 trillion and $120 trillion, and are rising at a rate of $2 trillion annually. By comparison, he says, the value of all tangible property in the U.S. -- homes, buildings, land, autos and personal property -- is $50 trillion. "The few trillion thrown at the banks looks like chump change compared to that," says Wharton health care management professor Mark Pauly.

At their current rate of growth, the two benefit programs will inevitably lead to a drain on the federal budget along with higher tax rates and borrowing costs, predicts Pauly. And while the Wall Street bailout and other government programs recently approved are a one-time expense, Medicare and Social Security obligations roll on year after year, he adds.

Olivia Mitchell, a Wharton insurance and risk management professor, raises additional concerns about the Social Security system, which she says has experienced a "triple whammy" in the past year. First, Social Security recipients in January received the largest cost of living increase -- 5.8% -- in 25 years. At the same time, the prolonged recession has led to a decline in payroll tax revenue. Finally, more unemployed older workers losing their jobs in the recession are likely to opt to receive Social Security benefits to replace their paychecks.