District officials who tried unsuccessfully to defeat the nation's first referendum guaranteeing the homeless "adequate overnight shelter" yesterday indicated they were softening their opposition to the landmark measure approved Tuesday by more than 72 percent of the voters.

Mayor Marion Barry, who along with the City Council has the power to invalidate the controversial referendum known as Initiative 17, said he is considering whether to pursue an expected court challenge. And City Council Chairman David A. Clarke said he believes the initiative could be implemented for considerably less than the $65 million D.C. Department of Human Services officials warned it might cost.

The plight of the homeless stirs "human emotions even the best politician can't fight against," said Barry. The recent death by fire of four homeless men who sought shelter from the cold in an abandoned building, coupled with publicity about a hunger strike by Mitch Snyder, a nationally known advocate for the homeless whose group sponsored the initiative, "even grabbed me," the mayor said.

Clarke, who voted for the initiative, said he regarded its overwhelming approval by more than 109,000 voters as a "statement of principle." Clarke said he disagreed with contentions by officials, contained in literature printed by the city and distributed at the polls, that called Initiative 17 a shortsighted solution to the complex problems of homelessness.

The initiative would require the city, which currently provides 753 shelter beds, to furnish overnight shelter that is "accessible, safe and sanitary and has an atmosphere of reasonable dignity" to any District resident. City officials have said that as many as 15,000 homeless people could be affected.

"I don't read it as saying we have to create public housing or provide mental health services for everybody," Clarke said. "When the temperature is zero, a roof over one's head and enough heat . . . is an improvement."

That is precisely the argument advanced by the Community for Creative Non-Violence and other advocates for the homeless who hailed the vote as an important victory with potential national implications.

Courts in three other jurisdictions -- New York City, Charleston, W.Va. and Los Angeles County -- have established the right to shelter, but the District is the first place where voters have addressed the issue.

"This is the first concrete test that an overwhelming majority of the public believes in the right to shelter," said Robert Hays, an attorney with the Manhattan-based National Coalition for the Homeless, a nonprofit consortium composed of advocacy groups from across the country.

"In other places you had laws on the books where lawyers could say, 'Look, the state welfare law requires the poor be cared for and the right to shelter is derived from that,' " said Hays, who filed the lawsuit that resulted in New York's 1979 shelter law, the nation's first. "What's important about D.C. is that lawyers couldn't find an existing legal basis so they had to go to the people."

As CCNV members were savoring their election victory and city officials were pondering their next move, some opponents expressed dismay at passage of the referendum, which has caused bitter divisions among local advocacy groups.

"There are people who won't come off the grates if you opened the new Marriott to them," said the Rev. John Steinbruck, chairman of the Mayor's Commission on Homelessness, which met yesterday. Steinbruck said he feared the referendum could cause the city to become a magnet for the homeless and create mammoth, squalid shelters similar to the one CCNV operates at 425 Second St. NW., three blocks from the Capitol.

But CCNV member Stephen O'Neil, who spearheaded the referendum drive, disputed the claim that the shelter would draw homeless people to Washington. "That certainly hasn't been the experience in New York," he said. "Homeless people are like everybody else. They want to stay in an area where they have friends or family, or where they grew up. People don't travel just to get shelter."