The District of Columbia Board of Elections and Ethics yesterday threw out a challenge by a group of ministers seeking to block a May 6 referendum of legalizing a lottery and other forms of gambling in the city.

The board's action moved the initiative one step closer to the ballot. Board workers now are examining signatures of registered voters on petitions seeking the referendum to determine if the required 5 percent of registered voters in five of the city's eight wards signed them.

A total of 200 randomly selected signatures are being checked in each ward and a report of the findings is expected to be given to the board tomorrow, according to William Lewis, the board's general counsel. The board then is expected to vote on the initiative, which would be on the same ballot as the city's presidential primary.

The initiative is simple, but far-reaching. Voters would decide whether to legalize city-run lotteries and daily numbers games like the ones in Maryland, pari-mutuel wagering on jai alai and dog racing, bingo games and raffles and social gambling where no organizer reaps a profit.

The initiative would not legalize wagering on any other sports, such as horse racing or professional football, or permit casinos in the District of Columbia.

Several ministers who are members of the politically influential Committee of 100 Ministers challenged 3,379 of the 21,462 petition signatures that had been collected by paid workers for the DC. Committee of Legalized Gambling, a pro-gambling group.

Since only 12,451 valid signatures are required to get the initiative on the ballot, the board rejected the ministers' challenge of the 3,379. If all the challenges were upheld, there still could have been 18,083 valid petition signatures.

"Frankly, there's strong cause for optimisim that the initiative will be on the ballot," Richard K. Lyons, a lawyer for the pro-gambling committee, said after yesterday's board action.

The Rev. John D. Bussey, a Baptist minister and gambling opponent, declined to predict whether the initiative is now likely to make the ballot, but said, "I don't look for a miracle."