The US regulator in charge of state-backed mortgage firms Fannie Mae and Freddie Mac has rejected an Obama administration plan to ease the housing crisis by forgiving some outstanding home loans.
Responding to pressure from President Barack Obama's White House to use debt forgiveness to help heal the depressed housing market, Edward DeMarco, acting director of the Federal Housing Finance Agency, said.
Mr DeMarco said the independent federal agency, in charge of taxpayer-supported Fannie and Freddie after a 2008 government rescue, would not participate fully in the program aimed at preventing foreclosures.
The program, which previously has focused on refinancing mortgages, has languished since its inception. The two firms back a majority of mortgages in the United States.
Even with the sweetener of Treasury department cash, Mr DeMarco said the plan to forgive debt was unacceptable.
"FHFA has concluded that the anticipated benefits do not outweigh the costs and risks," he said.
The FHFA has multiple responsibilities to conserve the assets of Fannie and Freddie, maximize assistance to homeowners to avoid foreclosures and to minimize the aid expense to taxpayers, he noted.
He said the program, known as HAMP, would not obviously improve the prospects of slowing foreclosures and would cost taxpayers more.
The decision is a blow to Mr Obama's hopes of righting the housing market with just 99 days to go before the presidential election.
The US Treasury secretary, Timothy Geithner, responded swiftly to Mr DeMarco's decision.
"I am concerned by your continued opposition to allowing Fannie Mae and Freddie Mac to use targeted principal reduction in their loan modification programs," Mr Geithner wrote in a letter to Mr DeMarco, released by the Treasury.
Mr Geithner acknowledged that Mr DeMarco, as the FHFA's acting director, had the sole legal authority to make the decision for the government-sponsored enterprises.
"However, I do not believe it is the best decision for the country, because, as we have discussed many times, the use of targeted principal reduction by the GSEs would provide much needed to help to a significant number of troubled homeowners," he said.
The Treasury chief also cited the benefits of helping repair the housing market, still in crisis six years after a price bubble collapsed, which would in turn benefit taxpayers as the economy improved.
Mr Geithner appealed to Mr DeMarco to reconsider his decision.
The American Bankers Association welcomed the FHFA's "prudent and thoughtful approach that considered the full costs and benefits of principal reductions".
A wave of foreclosures has been a key factor holding down home prices as buyers snap up distressed properties at bargain prices.
Foreclosure filings rose annually in the second quarter for the first time in two years, according to a RealtyTrac report released in July.
One in 126 homes in the country had at least one foreclosure filing.
Election swing-state Nevada had the highest state foreclosure rate: one in 57 homes. Arizona, Georgia, California and Florida rounded out the top five.
Mr DeMarco said he has unveiled to Congress several housing-related initiatives, including further help for borrowers looking to refinance their mortgages.
Fannie and Freddie, saved from collapse amid the 2008 financial crisis, have cost the government around $US150 billion ($A143.59 billion) in taxpayer funds to bail out.
In February, Mr DeMarco said he believed the two companies would never be in a position to repay the bailout.