Before the lending excesses that led to the crash, Ms. Bair said in an interview this week, banks generally refused to make loans on which repayments would be more than 35 percent of income, and often had lower limits. “There is,” she said, “a lot of room under Q.M. to make mortgages that should not be made.”

That brings us to Q.R.M. — the qualified residential mortgage. The six regulators that are supposed to agree on rules for that put out a proposal in 2011 that gave in to the banks on many issues, but not all. The banks reacted with anger, and the latest proposal is a virtual complete surrender. It essentially says that any mortgage that meets qualified mortgage standards will meet the higher ones as well.

“The result,” Mr. Frank wrote in a comment letter, “would be two categories, those that fall below standards and probably shouldn’t be made, and those that could be made and would not be subject to risk retention.”

“I am not surprised,” Mr. Frank added, that “the overwhelming majority of commenters who are interested in building, selling or promoting the sale of housing to lower-income people support effectively abolishing risk retention. I should note that if all of these people were correct in their collective judgment, we would not have had the crisis that we had.”

Three fellows of the American Enterprise Institute — Edward J. Pinto, Peter J. Wallison and Alex J. Pollock — agree. “With the demise of an independent Q.R.M.,” they wrote in a comment letter, “the credit quality objective of the Dodd-Frank law has been lost.”

Essentially, many of those who want to effectively abolish the Q.R.M. category fear that if lenders are forced to retain some risk, such loans will either not be made or will be prohibitively costly. They seem to take for granted that no bank will be willing to retain risk.

Thus the Virginia Housing Coalition, which supports affordable housing, warned in a comment letter that a 20 percent down payment requirement “would drastically limit access to mortgages and would put homeownership out of reach for low and moderate-income families, first-time home buyers, and disproportionally affect African-American and Latino families.”