It is unclear how many homeowners would be rescued from foreclosure through a plan proposed by Rep. Barney Frank (D-Mass.) that is gathering steam in Washington.

Frank himself now says it is “irrelevant” how many people will be helped under the plan, which Congress could take up over the next month.

Facing the worst housing market in decades, members of both parties are scrambling to throw a lifeline to at-risk borrowers, and aspects of Frank’s plan, which he is working on with Senate Banking panel Chairman Chris Dodd (D-Conn.), have already been embraced by the Bush administration.

Yet some on the outside have expressed doubts that it will help the 2 million people his office initially indicated could be aided.

The industry is generally in favor of Frank’s proposal because it would be voluntary and would essentially give lenders and mortgage services another option to avoid foreclosure other than freezing interest rates or otherwise easing loan terms.

But the voluntary nature of the plan also makes it tough to pin down just how many would participate.

“That’s the million-dollar question,” as one industry lobbyist put it.

“We’re hard-pressed to see them getting their numbers,” said a financial services lobbyist. He added that an initial review of several companies shows that the proposal would not likely generate the 1 million to 2 million loans as drafted.

Nonetheless, momentum for Frank’s plan is clearly building.

After taking more timid steps to help borrowers, the Bush administration is now embracing its tenets, which would have the Federal Housing Administration (FHA) guarantee refinanced mortgages only after lenders shrink them so they are more affordable to borrowers.

The administration is working on a similar proposal, centered on the FHA, which it plans to implement through regulatory changes and on a much smaller scale.