District officials and several Council members, pushed by increasingly strong threats of funding cutbacks from the federal government, have concluded that the city no longer can avoid raising its drinking age to 21, as have all but seven states.

In a significant boost for proponents of the higher drinking age, Mayor Marion Barry last week announced his support for the change. The drinking age is 18 for beer and wine in the District and 21 for liquor, while Maryland and Virginia in recent years approved 21 as the minimum drinking age for all types of alcohol.

A substantial majority of D.C. Council members has opposed raising the drinking age, arguing that 18-year-olds are adults in society for most other purposes. However, several key members said in interviews last week that they are rethinking their position and predicted that the city eventually will succumb to federal pressure.

"With the pressure from Congress and constituents, I suspect it the 21 drinking age will go through," said council member Polly Shackleton (D-Ward 3), a member of the council's Consumer and Regulatory Affairs Committee, which has jurisdiction on the matter.

Residents and businesses in Georgetown, complaining of a proliferation of bars catering to noisy teen-age crowds, have supported raising the drinking age.

The issue affects about 53,620 18-to-20-year-olds who are either permanent residents of the District or who go to college here, according to the D.C. Restaurant and Beverage Association, which opposes the change.

The association predicts that up to 13 percent of the bars and restaurants in the city would close if the 21-year drinking age went into effect.

The restaurant association estimates loss of sales tax revenues to the District from the change at $6 million a year, higher than a threatened loss in federal highway funds, but city administration officials estimate the sales tax loss at between $700,000 and $1 million.

By a 4-to-1 vote, the council committee last year killed a proposal to raise the drinking age to 21. Of the four in the majority, only Committee Chairman John Ray (D-At Large) stated last week that he definitely will not switch his vote.

Ray had predicted earlier that after the mayor came out in support of the change the council would approve it.

"Maybe I won't vote," said Shackleton, who opposed the measure last time. "I know my constituents want it, or most of them do . . . . I don't believe in it. I think it's wrong," she added in an interview from California where she is vacationing.

Last week, some members of Congress threatened to squeeze the District even harder if it is not swayed by the imminent loss of $2.6 million in highway funds in fiscal 1987, which begins Oct. 1, and a cutback of $5.2 million for each fiscal year thereafter.

The federal Department of Transportation's prospective cuts in highway funds have been highly effective in goading all but seven states to raise the their legal drinking age to 21.

The District is even more vulnerable to threatened funding reductions than other areas because it relies heavily on the federal government for yearly contributions and because Congress has direct control over the city's budget authority.

"If we were not harassed, with a gun at our heads, we would never do it," said council member Frank Smith (D-Ward 1), who voted in committee against raising the drinking age.

Smith said that if the mayor provides the council with figures indicating a major impact from federal funding cuts, "I guess I could be persuaded on the basis of that."

"In the end, we can't afford to lose the federal funds," said council member H.R. Crawford (D-Ward 7). Crawford, a strong opponent of raising the drinking age, said he would vote against the change "at this point," but indicated that going to 21 would be inevitable with the federal government determined to see it happen. "They are putting us over a barrel," he said.

Council Chairman David A. Clarke, whom the Barry administration counts as an opponent of raising the drinking age, was invited to appear before a Senate subcommittee, but Ray spoke on behalf of the council instead. The chairman did not return repeated phone calls to discuss the issue last week.

In passing legislation to reduce highway funding of states that refuse to raise the legal drinking age, Congress relied on statistics, disputed by opponents, showing that a higher drinking age saves lives by reducing the incidence of drunk driving.

"Our studies indicate that states raising their minimum drinking age show a 13 percent reduction in fatal accident involvement among drivers affected by these law changes," Diane K. Steed, the National Highway Traffic Safety administrator, testified during Senate hearings last week.

Ray said earlier at the hearing: "We could save more lives by outlawing amusement parks, by outlawing football . . . . If we are going to base this on statistics . . . we should raise the drinking age to 25."

In announcing his support for the higher drinking age on Wednesday, Barry said he wanted the change to take place immediately, with no transition to exempt current 18-to-20-year-olds as some states have tried.

The mayor said he intends to submit both permanent and emergency legislation to the council when it reconvenes in September.

Maryland and Virginia each approved a transition period, with Virginia's 21 law to be fully phased in next July.

So far, most states have conformed under congressional pressure. When the federal law passed in 1984, 23 states had a 21-year minimum. But now 43 have adopted that standard, according to congressional and U.S. Department of Transportation figures.