As much as $20 million a year will be at stake for the cash-pinched city government when District of Columbia voters decide May 6 if the nation's capital should become a center for legalized gambling -- with a city-run daily numbers game and parimutuel betting on dog racing and jai alai.

Las Vegas-style casinos with slot machines and roulette wheels sports betting and horse-race wagering would not be legalized. But bingo games and private social betting such as poker would be allowed.

The referendum is the first legislative initiative to be voted on in the city's history. If approved, it would permit legal gambling in the District for the first time since 1908, when the old Benning Horse Race Course in Northeast Washington closed.

Using the slogan "D.C. Dollars for D.C.," gambling proponents -- who include some of the most prominent members of the District's political establishment -- claim that legalized wagering would help solve the city's current financial crisis by capturing some of the money D.C. gamblers now bet legally in other states and illegally in the District.

Supporters of legalized gambling include D.C. School Board President R. Calvin Lockridge and hardware and lumber store executive John W. Hechinger. Other backers of the gambling proposal include well-known Washington residents who are investors in one of the firms seeking to bring jai alai, a fast-paced Spanish game, to the District if the referendum passes. They include realtor Flaxie M. Pinkett and Delano E. Lewis, assistant vice president of C&P Telephone Co.

"Gambling is a form of recreation -- the lottery for poor people, jai alai for more middle class," said Brant Coopersmith, Washington-area director of the American Jewish Committee and chairman of the D.C. Committee on Legalized Gambling. "I've never been any place where there's not a lottery. Why should this capital be any different?"

The loudest arguments against passage of the referendum are being voiced by ministers, most of them black and most of them Baptist. They view betting as sinful and immoral, and say they fear its legalization here will lead to more broken homes, higher crime rates and longer welfare rolls.

"Legalized gambling is a school for the matriculation of people who want to be criminals," said the Rev. Andrew Fowler, pastor of Capital View Baptist Church in Northeast Washington and executive Secretary of the Committee of 100 Ministers.

The churchmen also oppose the measure because, they say, tax money from nongambling sources would have to be used to launch gaming operations, noncity residents would be permitted to own gambling operations and one provision of the measure would seem to open the door for other forms of gambling.

"We'll end up with casinos," said the Rev. John D. Bussey, pastor of Bethesda Baptist Church in Northeast Washington. Gambling supporters say that is not so.

Despite the significant social and economic impact legalized gambling could have, most of the city's more prominent political leaders and most influential special interest groups have shunned active involvement in the campaign.

Mayor Marion Barry has taken a hands-off-till-after-the-vote position. Del. Walter E. Fauntroy has been preoccupied with other issues. The city's business community, organized labor groups and gay activists have refrained from active involvement.

Many of the ministers of larger and more influential churches are taking only a token role in the antigambling crusade, and some outside the coterie of old-line clergy bound by tradition concede that legalized gambling in Washington may be an idea whose time has come.

"I think we're going to have gambling in the nation's capital," said the Rev. A. Knighton Stanley, pastor of Peoples Congregational Church in Northwest Washington.

Stanley said he is opposed to gambling as "Another signal of moral decadence." But he conceded that given the choice, his 1,500 parishioners would vote 2 to 1 in favor of legalized gambling.

In many respects, the referendum campaign has been a silent issue in Washington, a secular town where thousands bet regularly on the legal lottery in Maryland and a $300 million-a-year illegal numbers game thrives; where churches are said to frequently run buses to the race tracks, office sports betting pools are commonplace and even the mayor of the city admits that he regularly plays poker in private and bets on the games -- something that technically is illegal.

The referendum on which the city's 241,893 registered voters can act is an all-or-nothing proposal -- a package deal that can be passed or rejected only in its entirety. It was written not by District legislators, but by gambling proponents.

At stake in the referendum are millions of dollars in prizes that gamblers could win and, after expenses, perhaps $35 million or more that, under the proposed 43-page law, would be divided three ways.

An estimated $20 million would go to the D.C. government to finance authorized programs for which no funds are otherwise available. The remainder would be given to public and private programs in special education and to nonprofit service organizations such as the United Planning Organization and the Washington Urban League.

The city is currently facing a projected budget deficit of $172.3 million for which Barry has yet to prescribe a satisfactory solution. City budget officials estimate that future revenue gaps could be even larger.

At the same time, inflation is driving up the cost of providing city services, a decline in federal funds is forecast, and there is strong citizen resistance to tax increases.

If the District did receive an extra $20 million from gambling, it would be an amount equal to that gained by increasing all property tax rates in the city by 14 cents per $100 of assessed value.

The gambling law would impose penalties for various betting violations and create a five-member gaming control commission, whose members would be appointed by the mayor with the consent of the City Council.

The commission would have the power to award lucrative contracts to companies that produce lottery equipment and other gambling paraphernalia, and to set a wide variety of regulations that would be needed to police legalized gambling, which in other states has often led to widespread corruption.

The story of how the District came to have a gambling referendum on the May 6 ballot centers on the bizarre twists and turns of maneuverings on the City Council.

William R. Spaulding (D-Ward 5), chairman of the council's Government Operations Committee and an adamant gambling foe, refused last year to even consider a proposal that called for an advisory referendum on gambling. "We had more important things to do than follow that route," he said.

As a result, gambling proponents wrote their own wagering legislation and then collected more than the required 12,451 signatures of registered voters to get the initiative on the ballot.

"The fact people are voting on this referendum is attributable to the City Council's lack of guts," -- its unwillingness to be publicly counted on a controversial issue, says Martin E. Firestone. A D.C. lawyer, he helped draft the gamling measure and has a 5 percent interest in a group called Washington Jai Alai, which is seeking to bring the sport to the nation's capital if the referendum is approved.

"There's nothing we can do now," said Council member David A. Clarke (D-Ward 1), who proposed the advisory referendum with Council Chairman Arrington Dixon, a supporter of gambling. "That's the shame of it all. We've got a very comprehensive bill written by amateur legislators."

Mayor Barry was an ardent supporter of legalized gambling while a member of the City Council. But by 1978, when he ran for mayor, the possibility of a referendum on the issue had surfaced, and Barry, like many other politicians, abandoned public support for it.

Even though he campaigned two years ago with the slogan "Take a Stand," Barry publicly has taken a fence-straddling position on the initiative, saying the D.C. voters "don't need the mayor to help them make up their minds."

The city's other top elected official, Del. Fauntroy, a Baptist minister opposes passage of the measure, according to a spokesman, because it offers "a false illusion to the poor" and "tangentially because of how (gambling) affects the District's image."

In recent months, however, Fauntroy has been more concerned with full voting representation for the District, peace in the Middle East and the presidential campaign of Sen. Edward M. Kennedy.

If the referendum passes, Congress would still have 30 legislative days after the initiative in which to veto the measure if it wants, just as with laws passed by the City Council. Various Capitol sources say there has been little discussion of the issue so far.

Some city officials have expressed concern that the passage of the referendum could hurt the city on Capitol Hill, not because of congressional oppostion to gambling, but because in the past, Congress has reduced the federal payment whenever the city raised more revenues such as those expected to come through legalized gambling.

The campaign over the referendum offers a clash between the colorful, often energetic and moralistic outlook of many of the city's ministers, and the cool-headed, well-financed secular pragmatism of the District's power elite.

The Rev. John D. Bussey, the 50-year-old pastor of Bethesda Baptist Church in Northeast Washington, is chairman of the two groups formed to fight the gambling measure, Anti-gambling Inc., and Citizens Against D.C. Initiative No. 2 (D.C. Initiative No. 1 was a proposed referendum on the convention center that never came to a vote.) The interfaith Committee of 100 Ministers is also playing a key part.

Bussey says he knows first hand of the pitfalls of gambling. "As a person, I got tied up with it, cards, craps, numbers," he recalled. "It's contagious. It's something that will make you spend your bread money." Bussey said he quit gambling 27 years ago when he "saw my children with their feet on the ground."

Shortly after gambling proponents got the referendum on the same May 6 ballot as the presidential primary, the ministers grandly envisioned a $300,000 campaign to defeat D.C. gambling.

The ministers hired James Rinker, 30, a legislative assitant starting a political consultant's firm, and he produced two issues of a four-page tabloid called "The D.C. Plain Truth." It was filled with antigambling articles. c

But the publication of further issues was abruptly stopped when the ministers were unable to raise enough money to keep it going. The two antigambling groups have so far raised a bit less than $11,000 mostly from churches and their members, and spent almost all of that, according to Bussey. c

"Much of our problem has been our political inexperience," Bussey said. "I'm a Christian minister. I'm way out of my field."

The only other organized group seeking to defeat the measure is the Fund for Animals, which says it is against the referendum because the group opposes dog racing.

The organization claims that rabbits, kittens and piglets are used as bait to train the greyhounds to run faster. The group further claims that 80 percent of the dogs that race are killed when they are not fast enough to win races anymore.

The chief progambling organization is the D.C. Committee on Legalized Gambling, which collected enough signatures of registered voters to assure the referendum's place on the ballot.

Many of its members were also members of the city's now disbanded Gambling Study Commission, which recommended that gambling be allowed in Washington. The involvement in the gambling drive of many well-known persons in the city was virtually unnoticed until their names surfaced in a court suit connected with the referendum.

The committee is a diverse group of some of the city's best known people, such as Hechinger, Lockridge, developer Theodore R. Hagans, former D.C. corporation counsel Charles T. Duncan and civil rights attorney Joseph L. Rauh.

"I'm very much in favor of the (legalization of the) numbers," Hechinger said, in the hope that some of the city's illegal numbers games might be driven out of business.

Another gambling supporter, retired Census Bureau official Jerry Cooper, said legalized lottery operations "would give some relief to the District's small businesses," which might regain sales they lost to Maryland stores when Maryland instituted its lottery in mid-1976.

The gambling committee has run a low-keyes campaign. It has not raised the $100,000 it had hoped to raise and would not be happy to collect $75,000, its members say.

The committee has already spent about $50,000 -- a large part of it to collect signatures for the referendum drive -- and is $22,000 in debt. But even with its lower than expected revenues, the gambling group has outspent the ministers by about 5 to 1.

Washington Jai Alai, a group seeking a jai alai license here if the measure is approved, has made nearly $9,000 in loans and contributions to the gambling effort. The D.C. Retail Liquor Dealers Association and its individual members have donated $5,000. Many of the liquor dealers want gambling approved so they can operate lottery sales outlets like Maryland stores, whose business has increased with the advent of that state's lottery. Four companies that sell lottery equipment have also donated $19,000 to the gambling drive.

The gambling group has recently placed posters on the back of Metro buses and is using a telephone bank to encourage those who signed the petitions to get the referendum on the ballot to vote May 6.

"The key will be to get out the vote," said gambling proponent Firestone. "We remain confident that the majority favors gambling here. But the city has a history of low voter turnouts. We've got to concentrate on getting the people to the polls."

Bussey has indicated that if the measures does pass May 6, he might campaign for its rejection on Capitol Hill, soliciting support from throughout the country.

Bussey said he supports home rule for the District. But, he said, "We've got to remember this is still the nation's capital. The conduct we make for the nation's capital is the image we set for the country."