The government may need to back home mortgages indefinitely to keep the broader housing market from going into a tailspin every time there is a financial crisis, Federal Reserve Chairman Ben Bernanke said yesterday.

In a speech to a forum on housing finance, Bernanke argued that government-sponsored companies Fannie Mae and Freddie Mac have played a crucial role propping up mortgage lending throughout the current financial crisis, even while purely private lending has shut down. But the Fed chairman said that, at some point, Fannie and Freddie need to be overhauled.

Bernanke was offering an opening salvo in what is likely to be a long debate over what to do with the mortgage finance giants, which the government effectively took over in September. Bernanke made clear that a scenario in which Fannie and Freddie went back to their old structure - of independent companies with implicit government backing - would be fraught with problems. He laid out several alternatives, without endorsing any of them.

"Everybody's coming to the table laying out their ideas," said Howard Glaser, a consultant in the housing finance industry. "Bernanke was giving a menu of options more than anything else. But he is clearly saying that there's going to be a big government role in providing mortgage liquidity."

Also yesterday, J.P. Morgan Chase said it would suspend foreclosures for the next 90 days on its mortgage portfolio, as it tries to sculpt a long-term ways to deal with the deepening housing crisis.

Both Bernanke's speech and J.P. Morgan Chase's action show how government and the private sector are in the early stages of grappling with the fallout of the most severe financial crisis in generations, one rooted in American home mortgages. Bank regulators and the Treasury Department are considering ways to try to help people at risk of foreclosure. Congress and the next administration will likely have to grapple with myriad issues, including the fate of Fannie and Freddie.

Bernanke emphasized that during deep financial crisis, very few mortgages have been issued that did not have implicit federal backing. This, Bernanke said, demonstrates the need for some government role in lending.

"At least under the most stressed conditions, some form of government backstop may be necessary to ensure continued securitization of mortgages," Bernanke said his speech, which was delivered by videoconference to the forum at the University of California at Berkeley.

He expressed his discomfort with the old structure, in which Fannie Mae and Freddie Mac were publicly chartered companies that nonetheless tried to maximize returns for shareholders. That, Bernanke noted, created major risks for the financial system as a whole, exposed the government to huge potential losses, and simultaneously enriched shareholders.

"We must strive to design a housing financing system that ensures the successful funding and securitization of mortgages during times of financial stress but does not create institutions that pose systemic risks to our financial markets and the economy," Bernanke said.