WASHINGTON — A mortgage rescue to help hundreds of thousands of struggling homeowners avoid foreclosure and get more affordable loans passed the Senate overwhelmingly yesterday, but faces a bumpy road amid continuing turmoil in the housing market.

The 63-5 vote reflected a keen interest by Democrats and Republicans in sending election-year help to distressed homeowners. The plan lets homeowners buckling under mortgage payments they can't afford keep their homes and get more affordable mortgages backed by the Federal Housing Administration. Banks that agree to take substantial losses on those distressed loans could avoid costly foreclosures and be assured of recovering at least some money.

The new program would let the FHA insure as much as $300 billion in new mortgages, helping an estimated 400,000 homeowners.

It still faces challenges, however, with the House planning to rewrite key details and the White House threatening a veto without major changes. President Bush objects to the $3.9 billion set aside in the measure to buy and rehabilitate foreclosed properties — something the White House said would help lenders, not homeowners.

Key players are bracing for intense negotiations to resolve the differences between Senate and House. They hope to smooth over disputes with the White House at the same time, to produce a bill Bush could sign later this month.

The measure includes a long-sought modernization of the FHA and would create a new regulator and tighter controls on Fannie Mae and Freddie Mac, the government-sponsored mortgage giants. It also would provide $14.5 billion in housing tax breaks, including a credit of up to $8,000 for first-time home buyers.