Bucking a veto threat, 39 Republicans joined Democrats in backing the bill, the centerpiece of a broader housing package that marks Washington's most aggressive response to the housing crisis.

The measure aims to unfreeze mortgage markets by expanding the Federal Housing Administration's reach and strengthening mortgage giants Fannie Mae and Freddie Mac. It also would create a $7,500 tax credit for first-time homebuyers to try to boost sales and slow plummeting home prices.

House GOP leaders blasted the bill as a bailout for speculators and irresponsible borrowers. But the bill, sponsored by House Financial Services Committee Chairman Barney Frank (D., Mass.), gained strong support from rank-and-file Republicans worried that escalating foreclosures are ruining lives and decimating neighborhoods.

Despite President Bush's condemnation of the bill this week, White House officials seemed to leave the door open to negotiation. In the Senate, key Republicans are working with Democrats on a similar plan.

"People are in a world of hurt. My sense is there's maneuvering room," said Rep. Fred Upton (R., Mich.), whose state has been among those hardest hit.

More than 1.2 million homes are in foreclosure, and three million more are forecast to join them over the next two years. Home prices have fallen more than 10 percent, and state and local tax collections are suffering. Polls show that the economy is voters' top concern.

The borrowers most at risk of foreclosure are those who have fallen behind on mortgage payments but cannot sell or refinance because their homes' value has fallen and they owe more than their homes are worth.

The Bush administration has tried to help such borrowers by urging banks to voluntarily reduce their mortgage debt. It also has eased eligibility standards so borrowers who have missed a few payments can qualify for cheaper loans insured by the government through the FHA. But those initiatives have helped relatively few families.

Frank's proposal calls for the FHA to respond more aggressively, by offering to insure mortgages for even the least creditworthy borrowers if their banks will forgive a portion of the debt and help them stay in their homes.

Lenders would have to take a significant loss, letting borrowers pay off their original loans with new loans worth no more than 90 percent of their homes' new, lower value. Extra fees charged by the FHA would lower the payoff to lenders to 85 percent of a home's current value.

Borrowers would get more affordable monthly payments and an immediate equity stake in their property. If home values rise, the plan requires the homeowners to share their profits when they sell or refinance with the federal government.

The Congressional Budget Office says as many as 500,000 homeowners will benefit from the program. But more than a third of those are likely to default, it estimates, forcing the FHA to pay off their loans and take possession of their property at a cost to taxpayers of $1.7 billion.

The White House has balked at that price tag. But there are signs it is open to compromise. On Monday, Federal Reserve Chairman Ben Bernanke appeared to endorse Frank's plan. Treasury Secretary Henry M. Paulson Jr. and other officials have spoken favorably of it.

Yesterday, White House spokesman Tony Fratto said of Frank's plan: "As a basic concept, it's what we're already doing. But it's what we're doing on steroids."

How They Voted

Representatives from the Philadelphia area who voted for a bill to aid struggling homeowners were Robert E. Andrews (D., N.J.), Robert A. Brady (D., Pa.), Michael N. Castle (R., Del.), Charles W. Dent (R., Pa.), Chaka Fattah (D., Pa.), Jim Gerlach (R., Pa.), Tim Holden (D., Pa.), Patrick Murphy (D., Pa.), Allyson Y. Schwartz (D., Pa.), Joe Sestak (D., Pa.), and Christopher H. Smith (R., N.J.).

Voting against the bill were Frank A. LoBiondo (R., N.J.), Joseph R. Pitts (R., Pa.), and H. James Saxton (R., N.J.).