Bankers have begun to show cautious interest in a proposal to offer banking services in post office branches after U.S. Postal Service Inspector General David Williams clarified that the plan would be a partnership with banks rather than head-to-head competition. Williams envisions the Postal Service providing a marketplace platform that private-sector financial institutions could use to offer competing prepaid cards and other financial products. "The platform would be open to everyone — banks, credit unions and the credit card industry," he said. But the postal banking concept still faces big hurdles. Officials at the Postal Service itself have shown less enthusiasm for the concept than the inspector general's office, which operates as a separate advisory body.