HARRISBURG - A federal report shows that tightening supervision of Pennsylvania's Medicaid program is unlikely to produce the huge savings predicted by some critics, Gov. Rendell said Monday.

The estimated error rate in Pennsylvania's program was 4 percent in fiscal 2009, the November analysis by the U.S. Department of Health and Human Services showed.

That was less than half the 9 percent national rate and far shy of the 15.5 percent average error rate that state Auditor General Jack Wagner reported from his audits of county welfare offices conducted from 2005 through early this year.

Wagner, a Democrat, estimates that reductions in erroneous eligibility determinations could save the state hundreds of millions of dollars a year in Medicaid payouts. Republican Gov.-elect Tom Corbett has cited Wagner's findings as the potential source of major budget savings.

Wagner, who as auditor general has been a frequent critic of the Rendell administration, stood by his conclusions Monday.

"The federal report is based on information provided to the U.S. government by those claiming a lower rate. We have serious concerns about the methodology used in issuing this report," he said.

Medicaid is a federal-state program that helps provide health care for the poor, elderly, and disabled. In Pennsylvania, it is administered by the state Department of Public Welfare.

State taxpayers contribute about $7 billion of the more than $16 billion cost of the program, according to acting Public Welfare Secretary Michael Nardone.

Rendell, who will leave office in less than a month, asserted that the report was "conclusive proof" that Wagner's conclusions were "completely out of line." He said it showed the success of his administration's efforts to minimize errors.