UnitedHealth Group Inc., Humana Inc. and other health insurers will collect $54 billion more from Medicare than the government would spend providing care directly over the next four years, a U.S. auditor said.

A "relatively small" share of the money, 11 percent, will go to extra benefits under the Medicare Advantage program, which covers 9 million elderly people who chose subsidized private plans for their care, the Government Accountability Office (GAO) said in a report Thursday.

The report fueled a new political attack by House Democratic leaders concerning Medicare Advantage, which will direct $86 billion to insurers this year on the theory that it provides care more efficiently than regular Medicare. Advantage costs the government 13 percent more than Medicare, according to official estimates. The optional program's extra benefits have attracted more than 20 percent of the 44 million Medicare-eligible Americans.

"Medicare Advantage does not contain costs, and there's no evidence that the value provided to beneficiaries is commensurate with the program's high price tag," said Michigan Democrat John Dingell, chairman of the House Energy and Commerce Committee, in an e-mailed statement. "The real beneficiaries of Medicare Advantage are the insurance companies."

The chairmen of several other House committees joined Dingell in criticizing the program, which is backed by President Bush and Republican lawmakers. Insurance industry supporters of Advantage plans say the private-sector coverage provides elderly members added services and lower copayments for the extra cost.

The GAO concluded that extra benefits for Medicare Advantage members are financed partly by higher premiums deducted from Social Security checks to the people not enrolled in private plans. The entire Medicare program cost $401 billion in 2006 and an estimated $430 billion in 2007. Spending is projected to grow to $467 billion this year and more in the future as the baby boom generation ages.

"There is no free lunch when it comes to Medicare Advantage," James Cosgrove, GAO's acting director for health care, told the panel.

The only Republican panel member to attend the hearing for more than five minutes, Dave Camp of Michigan, disputed the GAO findings, calling them "stilted" and unreflective of real-world experience.

"This really is a fake report with fake conclusions, and we're having this fake hearing about it so we can run to the media to make fake pronouncements," Camp said. "If the beneficiaries didn't see the real value in these plans, enrollment wouldn't have doubled since 2003."