The Department of Housing and Urban Development wants 50% of the loans Fannie Mae and Freddie Mac buy in 2000 to be to low- and moderate-income borrowers.
The requirement would be 48% next year. The current target, in force since 1997, is 42%.
HUD, which regulates the mission of the government-sponsored enterprises, said the plan would boost their affordable housing requirement to an estimated $2.4 trillion of loan purchases over the next 10 years.
That is $488.3 billion more than if current rules remain in place.
Franklin D. Raines, chairman and chief executive officer of Fannie Mae, said the agency would "stretch" to meet the proposed housing goals.
A Freddie Mac spokeswoman said her company was still talking with HUD about the requirements. Freddie needs to see the formula before it can say whether the company could meet the goals, she said.
Families are considered to have low or moderate income if they earn no more than their community's median. The national median is $47,800.
Under the 1992 Federal Housing Enterprises Financial Safety and Soundness Act, Fannie and Freddie were expected to target 30% of their purchases in 1993-1995 to low-income and moderate-income mortgages. The target rose in 1996 to 40%.
The target is up for renewal this year, and HUD's proposal is subject to approval by Congress. The Office of management and Budget will review the plan, and there will be a period for public comment.
Mr. Raines noted that Fannie Mae has met or exceeded the affordable housing goals since HUD formalized them in 1995. Fannie said that in 1998 its financing for minority households rose 75% as it provided 451,000 such families with $46 billion of credit.
Sixty-eight percent of Fannie Mae's low- and moderate-income housing credit in 1998 was distributed to people with incomes at or below 80% of their area's median, the company said. Thirty-seven percent went to those with incomes between 60% and 80% of the median, and 31% to those with incomes below 60% of the median.
Loans to low- and moderate-income families for single-family homes made up the same share of Fannie's and Freddie's purchases last year-38%-but the companies are not on equal footing in multifamily homes, the Freddie Mac spokeswoman said.
Ninety percent of Fannie's multifamily loan purchases are going to affordable housing, while Freddie is purchasing 93%, the Freddie Mac spokeswoman said. This gives Fannie an advantage that needs to be addressed, she said.
Fannie's multifamily book of business is four times the size of Freddie's.
HUD also said it was raising two other affordable-housing goals.
Fannie and Freddie would be required to increase their purchase of loans to families with "very low" and "low" incomes-defined as less than 60% and less than 80% of area median-to 20%, from 14%.
And the two government-sponsored enterprises would have to increase the loans they purchase in underserved areas-including central cities, rural regions, and minority and low-income communities-to 31%, from 24%.