Four Democratic mayoral candidates said yesterday that they would return money received from the real estate industry if rival John Ray, the leading fund-raiser in the campaign, agrees to do the same.

The pledge from Walter E. Fauntroy, David A. Clarke, Charlene Drew Jarvis and Sharon Pratt Dixon followed a candidates' debate Wednesday night, where Ray said he was prepared to join the other candidates in returning contributions from developers, landlords and brokers.

However, Ray said last night he would not return any of his contributions, adding that the only reason he raised the issue at the forum was to show "how ludicrous" Fauntroy's criticisms were of his real estate contributions.

"If Walter and the others think that accepting money from real estate developers is so bad, why do they take it in the first place?" Ray said, calling it a "non-issue."

"Walter's campaign is dead, and he's trying to put some life in it," Ray said.

Ray, a Democratic at-large D.C. Council member who has led his rivals in fund-raising and in polls, has come under fire from Fauntroy and others for accepting large sums of money from real estate interests.

"Ray has a reason to be concerned, because it is just an extraordinary amount of money from the real estate community," Dixon said. "It is a source of great concern and disquiet in the campaign."

Of the $668,584 raised by Ray through the beginning of June, 34 percent came from real estate developers, brokers and landlords, the largest amount and percentage of any candidate.

Clarke and Fauntroy also criticized a $25,000 independent advertising campaign by the Washington D.C. Association of Realtors on behalf of Ray.

Fauntroy questioned its legality, while Clarke demanded that Ray ask the group to halt the expenditures, saying that they leave the "strong impression that he is committed to one industry, to the detriment of the renters."

Meanwhile, Jesse L. Jackson, a candidate for one of two shadow Senate seats, told reporters that he does not intend to endorse or align himself with any other D.C. candidates seeking office this year.

Jackson, whose aides made some attempts to organize a Jackson slate last month, said he plans to devote his efforts to voter registration and a campaign on behalf of D.C. statehood.

He added, however, that such activity does "not necessarily" mean that he would support D.C. Council member Hilda H.M. Mason's bid to retain her at-large seat in the face of Mayor Marion Barry's announcement this week that he is a candidate for an at-large council seat.

Mason (Statehood) said she hasn't asked for Jackson's support, but added that "I just thought he would because he's working for statehood."

Jackson also told reporters at breakfast that he has abandoned efforts to try to persuade the Senate Democratic leadership to grant him floor privileges if he is elected to one of two positions to lobby the Senate for statehood.

Also yesterday, Clarke, the council chairman, picked up the endorsements of five local unions, in his first major show of support from the labor community -- although some of the unions also endorsed other candidates.

Local 400 of the United Food and Commercial Workers, one of the largest unions in the area with 40,000 members, announced that it was supporting both Ray and Clarke. The Amalgamated Transit Union Local 689 said it was supporting both Fauntroy and Clarke.

Clarke also was endorsed by the Operating Engineers Local 99, the Painters District Council 51, and Local 709 of the American Federation of State, County and Municipal Employees. Clarke was previously endorsed by the Laborers' Union Local 74.

"I'm gratified that these unions are willing to try to stand up and make a winner, rather than try to pick the winner," Clarke said.

Jarvis was endorsed yesterday by local 1610 of the Amalgamated Transit Union, which represents area Greyhound workers who have been striking since March 2.

At a meeting of union members supporting his candidacy, Fauntroy called on Ray to disclose the names of the persons controlling dozens of real estate partnerships that have given money to Ray's campaign. At the same time, he released the names of people controlling the partnerships and corporations that contributed to his own campaign.

Campaign finance laws in the District permit candidates to accept money from real estate partnerships without identifying the owners. But Fauntroy said that additional disclosure by Ray "would tell us if these real estate interests stand to benefit financially or otherwise from their financial contributions."

"I am concerned about the disproportionate amount of developer and real estate money that is behind him," Fauntroy said. "I know that he who pays the piper calls the tune."

Fauntroy also filed a complaint with the D.C. Office of Campaign Finance, questioning the validity of the $25,000 independent Metro bus and poster campaign on Ray's behalf by the Realtors association.

In a letter to the campaign finance office, Fauntroy attorney Wright H. Andrews complained that several top officials of the Realtors association have contributed money to Ray and are active in his campaign, thus violating the requirement that the advertising campaign be "independent" of Ray's mayoral campaign.

In a separate statement, Clarke charged that "the large amounts of money being spent on Mr. Ray's behalf by the real estate industry make a mockery of his much-ballyhooed offer to return campaign contributions from real estate interest."

Marianne Coleman Niles, the director of the campaign finance office, was not available for comment yesterday.

Donald R. Slatton, executive vice president of the Realtors association, said the expenditures on Ray's behalf "were completely legal."

"We have not been in contact with his campaign about them -- you're not supposed to do that," Slatton said. "We have scrupulously adhered not only to the letter of the law, but the spirit of the law."