Backers of a proposed District of Columbia gambling referendum announced yesterday that they will conduct a weekend blitz to collect 12,481 valid signatures needed to put the issue on the November 6 ballot.

Four D.C. City Council Members led by Chairman Arrington L. Dixon, an outspoken supporter of legalized gambling, attended a news conference and endorsed the campaign to collect the signatures.

The conference at the District Building was called by the D.C. Committee on Legalized Gambling, a citizen organization, two of whose directors are officers of a corporation that wants to conduct Jai Alai games -- with parimutuel betting -- in the city.

The two directors are Richard K. Lyon and Martin E. Firestone, both lawyers, who according to Lyon, each own 5 percent of the Washington Jai Alai Corp. Lyon said the names of other stockholders, all local, will be announced later.

Jai alai, a fast-paced game popular in Latin America, is a sort of cross between handball and tennis.

At one point, when the exchange between Lyon and some reporters became heated over Lyon's financial interest in gambling, Council Member David A. Clarke (D-Ward 1) defended the right of interest groups to use the ballot in at attempt to achieve their goals.

"What of it? What of it?" Clarke asked. "Groups with self-interest . . . that's what the initiative referendum is all about. It's no sin."

Another director of the gambling group is Buddy Weitzman of the D.C. Retail Liquor Dealers Association, whose members would probably sell tickets in a city lottery if it is legalized by the referendum.

The referendum also would legalize social gambling and such activities as church-sponsored bingo games and raffles.

Groups of Protestant ministers have warned that they will campaign vigorously against the gambling plan.

If the gambling proposal gets enough signatures, it probably will be the first issue to go on the ballot under a D.C. referendum procedure that went into effect last month.

Opponents of the planned downtown convention center also want a referendum November 6 on their proposal convention center also want a to block that project. Denied access to the ballot by the Board of Elections and Ethics, they have taken the issue to court.

Jerry Cooper, vice chairman of the gambling referendum committee, told yesterday's news conference that petition forms have been distributed to dozens of Catholic churches, grocery stores, convenience stores, barber and beauty shops and liquor stores.

Cooper said the 12,481 valid signatures must be submitted to the Board of Elections by 5 p.m. Monday. They must include at least 5 percent of the registered voters from at least five of the city's eight election wards. To provide a cushion, Cooper said the committee hopes to get 20,000 to 25,000 signatures.

Of the four council members who attended the news conference, only Dixon flatly endorsed the gabling proposal, saying the revenue -- an estimated $40 million a year for the city treasury -- was needed.

Clarke, Polly Shackleton (D-Ward 3) and Betty Ann Kane (D-At Large), in varying degrees, reserved judgement on the gambling proposal itself but said they supported the drive to collect signatures as a demonstration of democracy in action. CAPTION: Picture, ARRINGTON L. DIXON . . . endorses signature drive