(By DEREK KRAVITZ, AP Real Estate Writer) The Obama administration is blaming the three largest U.S. mortgage lenders for the failures of its foreclosure-prevention program. It says they've done little to help people at risk of losing their homes.Wells Fargo, Bank of America and JPMorgan Chase & Co. have failed to help enough people permanently lower their mortgage payments so they can stay in their homes, the Treasury Department said Thursday.