While politicians debate how best to cover the growing ranks of the uninsured, the federal government quietly is adding to those numbers by outsourcing service jobs. Under a 1965 law called the McNamara-O'Hara Service Contract Act, most contractors with service contracts of more than $2,500 are required to pay locally prevailing wages, plus fringe benefits or the cash equivalent. But some contract employees don't get either the health insurance or the extra cash.