WASHINGTON — Should the federal government bail out a homeowner who lied about her income, bought a house far bigger than she could afford and now, predictably, cannot make the payments?

What about someone with a terrible credit record who has repeatedly missed mortgage payments? Should the government agree to pay off the lender if that mortgage fails?

The Bush administration says no, which is one reason the White House opposes an ambitious Democratic plan to defuse the nation's housing crisis by sharply relaxing eligibility standards for federal mortgage insurance. Under the proposal, lenders would be encouraged to wipe out a portion of the debt on troubled loans in exchange for a promise that the government would pay off the mortgage if the borrower can't.

Democrats and some mortgage analysts predict the plan would save more than 1.5 million families from foreclosure, keeping them in their houses and helping to stabilize plunging home prices. But federal housing officials and other analysts are skeptical that the plan could help enough people to prop up the housing market. They say so many of the nation's approximately 3 million subprime borrowers are in such deep financial trouble that only a few hundred thousand are likely to qualify even under relaxed standards.

"It's going to be extremely difficult to reach a large portion of these borrowers," said Meg Burns, director of Single Family Program Development for the Federal Housing Administration. "Unless you transfer the risk and cost to the federal government, then they cannot be helped."

The chief author of the Democratic proposal, House Financial Services Committee Chairman Barney Frank, D-Mass., called his housing plan "experimental" and acknowledged that it's impossible to say how many homes ultimately could be saved.

"I told my staff, 'Don't say a million and a half. Let's just try to do the best we can,' " Frank said. "The more risk you take, then maybe the more good you can do. But it's a very inexact line. If you can help hundreds of thousands of families, I think that's a pretty good deal."

President Bush and key Republicans are strongly resistant, however, to helping people who have little hope of repaying or who willingly signed up for irresponsible loans.

"If we continue to refinance bad credit risks, we're just asking for another problem six months or a year from now," said Sen. Richard C. Shelby, Ala., the senior Republican on the Senate Banking Committee, which is considering a similar proposal. "There's some people — and I'm probably kin to some of them — that maybe shouldn't have ever bought a house."

The Frank plan is gaining momentum in Washington because it represents the best idea so far for dealing with a problem at the heart of the mortgage meltdown: homeowners who now owe the bank more than their homes are worth due to falling home prices. Ordinarily, a borrower who cannot make payments would sell or refinance. An estimated 8.8 million borrowers no longer have that option because proceeds from the sale or the new loan would fall short of paying off the old one.