The principal bankroller of the campaign to get a gambling referendum on the May 6 ballot in the District of Columbia is a group trying to bring the fast-paced Latin sport of jai alai to Washington.

The Washington Jai Alai Corp., led by a retired Long Island jeweler and including politcially prominent Washingtonians, gave a $6,000 loan to the D.C. Committee on Legalized Gambling, the chief umbrella group spearheading support for legalized gambling here, and contributed another $950 to the effort.

The combined loan and donation represents nearly one-third of the $22,000 the gambling group spent in collecting 13,520 signatures of D.C. registered voters to place the gambling initiative on the ballot.

The referendum was approved Wednesday by the D.C. Board of Elections and Ethics. If approved by the voters, it would legalize lotteries and daily numbers game like those in Maryland, bingo, raffles, parimutuel wagering on jai ali and dog racing and social gambling where the organizer reaps no profit.

The jai alai group is headed by Justin Shick, a 62-year-old jeweler who retired to Coral Springs, Fla., nearly three years ago, Shick, who said he gambles on jai alai almost every night in Miami, has a 45 percent interest in the corporation and helped recruit the Washingtonians with the aid of two local attorneys, Martin E. Firestone and Richard K. Lyon.

By recruiting the Washingtonians as stockholders, Shick said, he hopes to make his jai alai franchise proposal attractive to the gaming commission that would oversee gambling enterprises here.

Among those who have invested in Washington Jai Alai are Tyler Abell, a Washington attorney and former assistant postmaster general in President Johnson's administration (5 percent interest); former D.C. Corporation Counsel Charles T. Duncan (2 1/2 percent), developer Theodore R. Hagans Jr., chairman of D.C. Mayor Marion Barry's inaugural committee last year (5 percent investor), and Robert Grayson McGuire Jr., a funeral home president and former Board of Elections member (2 1/2 percent with his wife).

Abell, who pledged $25,000 to the jai alai group, said, like others, that Lyon and Firestone approached him about investing in the company.

"This is a gamble just like any other investment," Abell said. "I didn't enter it to lose money. Naturally I'd be happy if it were profitable."

Delano E. Lewis, an assistant vice president with the Chesapeake and Potomac Telephone Co., said he bought a 1.25 percent interest ($6,250) because "I understand it is a fairly good investment in other cities."

While Washington Jai Alai's bid for the D.C. franchise is by no means certain a stock prospectus envisions steadily growing profits that could total $12.8 million over the first five years, a figure based on the amount of gambling common at jai alai operations in Miami and Connecticut.

The battle over legalized gambling in the nation's capital is expected to be as spirited as if actual candidates were opposing each other. The politically influential Committee of 100 Ministers said yesterday it hopes to raise $300,000 in an effort to defeat the measure, with much of the money used for radio and television advertising.

In addition, the Rev. Raymond Robinson, the committee's president, said ministers will be asking their parishioners, mostly black Baptists, to help distribute literature and canvass neighborhoods to find those voters opposed to gambling.

For their part, the gambling committee leaders predicted a substantial majority would approve the measure and said they hope to conduct their own campaign in its support. However, Brant Coopersmith, the gambling committee's chairman, said no plans have been made yet for the pro-gambling effort.

Aside from the Washington Jai Alai group, D.C. liquor dealers are among the most ardent supporters of legalized gambling in the city. The liquor retailers say they have lost thousands of dollars in sales to nearby Maryland liquor stores that have the advantage of being able to sell daily and weekly lottery tickets.

While the ministers group is solidly against legalized gambling here, some gambling opponents conceded yesterday that the prospect of defeating the measure is not good.

The Rev. Robert L. Pruitt of the Metropolitan AME Church, a downtown congregation with about 5,000 members, described the chances of defeating the measure as "dismal."

"The people we're preaching to are also the people who are looking for the quick dollar through gambling," he said. "It's like prohibition. It's not really whether we win the fight, but just that the church takes the stand." n

Among the other investors in Washington Jai Alai are Flora L. Bress, widow of former U.S. attorney David G. Bress (2 1/2 percent); Bryant G. Harris, a local businessman (5 percent); Dr. Edward Mazique, a physician and early supporter of Del. Walter E. Fauntroy, and Mazique's wife, Frances (1.25 percent), and Dale Miller, a lobbyist represent Texas interests who was President Johnson's inaugural chairman in 1965, and his wife, Virginia (Scooter), 5 percent.

Lyon and Firestone also each have a 5 percent interest with their contribution coming in the form of their legal work for the firm, Lyon said.