The Department of Housing and Urban Development wants to help poor Americans become homeowners while making it harder, and sometimes impossible, for many middle-income people to buy houses, critics of the administration's FHA reform proposals charged this week.

Members of Congress, housing industry groups and consumer organizations differed sharply with HUD officials during a congressional hearing over how best to revive the ailing Federal Housing Administration's home mortgage insurance program.

HUD representatives said the administration's plan, which would require more cash from home buyers at the time of the sale and increase many buyers' monthly mortgage payments, is necessary to stem the losses. But opponents argued that such changes would hurt the Americans the FHA was created to help.

Rep. Barney Frank (D-Mass.) said HUD's plan would make it easier for families earning 50 percent of an area's median income to buy homes, but make ownership far more difficult for those earning the median income.

"That's not acceptable," he said. Frank was referring to HUD Secretary Jack Kemp's efforts to help low-income public housing tenants become homeowners.

The General Accounting Office and the Price Waterhouse accounting firm reported late last year that the Mutual Mortgage Insurance Fund, which has helped millions of Americans buy homes over the last 56 years, lost $1.4 billion in fiscal 1989.

The administration expects that 15,000 to 35,000 families who can afford FHA-insured houses now could not buy them if HUD's proposals become law. Estimates by the National Association of Home Builders, the National Association of Realtors and the Mortgage Bankers Association of America and other groups are higher, ranging up to 250,000 buyers who would be locked out of ownership.

Most of the administration proposals were included in the Senate housing bill passed two weeks ago. Under the bill, the upfront insurance premium charged for an FHA loan would remain at 3.8 percent of the loan amount, but FHA would charge an additional half a percentage point annually for up to 15 years on mortgages it considers riskier. These would be loans on which buyers made down payments of less than 10 percent of the loan amount.

Purchasers also would have to pay two-thirds of the closing costs in cash at the time of sale. Under existing law, down payments and closing costs can be covered by the mortgage, often leaving new owners with loans higher than the value of their homes.

The changes would add $30 a month to payments on a $75,000 mortgage at 10 percent interest and increase the amount of cash needed at settlement by more than $1,100. Under current law, buyers need less than $1,000 in cash at settlement.

A bill sponsored by Reps. Bruce F. Vento (D-Minn.) and Thomas J. Ridge (R-Pa.) would lower the up-front premiums. It also would "restore FHA to a pay-as-you-go system" by phasing in an annual premium, Vento said.

Industry groups and some members of Congress have called for an increase in the $124,875 limit on mortgages the FHA can insure to 95 percent of a state's median home prices.

HUD Undersecretary Alfred A. DelliBovi said the department does not favor such an increase because it does not believe the government should provide mortgage insurance for "high-income home buyers."

FHA's "historic and proper mission is to serve low- and moderate-income home buyers," he said. DelliBovi testified during hearings held this week by the housing and community development subcommittee of the House Banking, Finance and Urban Affairs Committee.

The GAO and Price Waterhouse said raising the ceiling on mortgages to 95 percent of state medians would would increase the FHA's business and income, but also would add to its risk. The amount of FHA insurance issued would more than triple, rising to $886 billion, said John M. Ols Jr., director of housing and community development issues for GAO. Ols told the subcommittee that the ceiling should not be raised until the FHA is financially sound.

HUD has proposed an increase in the amount of capital reserves the FHA must have to a minimum 1.25 percent of the amount of insurance it issues in the next few years, with an eventual goal of 2 percent.

DelliBovi said that while "poor management and lax monitoring" during the 1980s were major causes of past FHA losses, changes in the insurance program itself are needed

The major causes of FHA problems are economic downturns in several areas of the nation, declining housing values and the Reagan administration's backing of "very risky loans." He said the government should move quickly in making changes.

"We have to be sure this patient {FHA} is going to survive and get out of the operating room," he said. "I'm not at all sure it is."

But others believe such speed is not critical.

Ols said immediate action may not be needed but that it is important to consider "all the options" analyzed by Price Waterhouse at HUD's request. The three sets of options, submitted by HUD and by Sens. Alan Cranston (D-Calif.) and Alfonse M. D'Amato (R-N.Y.), all were financially sound but would have different effects on home buyers, the accounting firm said.

"It is totally inappropriate ... {to make FHA loans} less available to needy borrowers until we know what is really the major cause of the losses in the '80s," said Michelle Meier, government affairs counsel for Consumers Union. She said it is also unfair to saddle future borrowers with "burdensome" changes if government fraud, waste and mismanagement resulted in the unsound loans expected to go bad in coming years.

Rep. Henry B. Gonzalez (D-Tex.), chairman of the House Banking Committee and of its housing subcommittee, said the administration's reform measure was put together "before a thorough analysis of the Price Waterhouse report could take place."

He said the report may have "unnecessarily painted a bleak picture of the financial soundness of the FHA fund" and did not put enough emphasis on the "administrative neglect, mismanagement and fraud" at HUD during the 1980s.

The single-family home insurance program has a net worth of $2.6 billion, a dramatic decline from $7.8 billion in 1980, and still is dropping, according the Price Waterhouse study.

The House is expected to consider its housing measure next week.