Supporters of a bill to amend the Fair Housing Act of 1968 say on the eve of a vote in the House that the legislation may be in trouble.

The bill, which would give Housing and Urban Development broad powers to enforce the law prohibiting racial and other forms of discrimination in housing, has survived several attempts to weaken its impact.

In February a proposal to eliminate HUD's authority was defeated in the House Judiciary Committee. Early this month the bill finally moved out of committee reasonably intact and is scheduled for a vote on Wednesday.

But some supporters of the bill say they are worried. This week, James Haynes, president of the National Association of Real Estate Brokers Inc. (NAREB), the largest minority trade association in the housing industry, was in town to rally support for the bill.

"We say the ownership of a house ought to be an inherent right," Haynes said. "Many professional groups have recently agreed with us, but people are finding all sorts of technical reasons to oppose the bill."

The group that is leading the opposition is the powerful National Association of Realtors, which represents the industry majority. The association sent out thousands of letters on official House stationary and signed by Reps. Ronald M. Mottl (D-Ohio) and John W. Wydler (R-N.Y.). The letters asked local officials to express their opposition to the bill on the grounds that "it violates every principle of sound government because it puts the federal government directly in local affairs."

To lobby for passage of the bill, the minority association formed a "Democracy in Housing Coalition," made up of about 40 civil rights, community and professional groups including the NAACP, the National Urban League and the Congressional Black Caucus.

Darryl Hill, executive director of NAREB, says the amendments are urgently needed because discrimination in housing is "rampant."

"We want the law to work and it has not worked," he said. "It is one of the most important pieces of legislation for black Americans in modern times.

"If there was true integration in housing, you'd have true integration in other areas."

The brokers group feels that in addition to protecting minorities against discrimination, the bill could have a beneficial economic effect for the entire housing industry.

"You don't have to discriminate to make money," Hill said.

Currently, the only recourse available to renters or buyers who feel they have been discriminated against is to go to court at their own expense. Under the amendment, the government would assume the burden of investigation of cases of alleged discrimination and would have the power to levy fines up to $10,000.

"The average person who discriminates is banking on the fact that the person discriminated against will not follow up," Hill said.

The law would also protect the physically and mentally handicapped and outlaw the practice of redlining.

Meanwhile, Hill and James met Tuesday with the staff of presidential assistant Stuart Eizenstadt to present the association's proposal on how to make mortgage money more available at lower interest rates.

The plan calls for the government to issue securities -- called mortgage market certificates -- on the open market. The rates on these certificates would be competitive with other securities. The money from the sale would be loaned to mortgage bankers at a lower rate, with the provision that the banks charge no more than 12 percent.