Negotiations that could avert Washington's first hotel strike in 35 years remained deadlocked on key issues yesterday and both sides prepared for a possible walkout as tonight's midnight strike deadline approached.

The Hotel and Restaurant Employees Union Local 25, which represents some 6,000 maids, bartenders, waiters, waitresses and busboys at 24 of the city's major hotels, does not have a strike fund.

But union leaders, buoyed by a unanimous membership vote Sunday night authorizing a strike, announced that they were discussing sale of a $1.5 million union-owned piece of land here and borrowing strike-fund money from their international affiliate. Union leaders also issued strike instruction sheets to union members.

"They've convinced me there is going to be a strike," Ron Richardson, the union's executive director and chief negotiator, said of the hotel association negotiators. "They don't seem to want to negotiate, at least seriously," Richardson added as bargainers recessed for dinner after talks in the Midtown Motor Inn at 12th and K streets NW.

In an effort to show solidarity on the other side, managers of the 24 hotels -- including the Madison, Hay-Adams, Mayflower, Hyatt Regency, Watergate and the Hilton and Sheraton hotels -- said that they have signed a lockout clause pledging that all hotels involved in the negotiations will lock out their union employes if any hotel is picketed.

The hotel officials refused to say specifically what they would do if the unionized workers did not report for work at 6 a.m. Wednesday, the first shift due after tonight's midnight deadline. "We're professional planners and planning for a strike just makes good business sense," said Edward MacMillan, an owner of the International Inn on Thomas Circle and the head of the hotel owners' negotiating team.

Allen G. Siegel, the chief negotiator for the Hotel Association of Washington, said the association does not want a strike, but he said the union has been unrealistic in its demands. They include an annual raise that would amount to $32 a week during each of the next three years, new arbitration procedures, a greater emphasis on seniority and more pay for workers whose hotels cater to tour groups.

"In the past, hotels were riding the crest of prosperity and that attitude favored the unions," Siegel said. "But at this time, the forecasts for the hotel industry are different and we cannot be so flexible."

Besides tourists, a strike would hurt Washington's lunchtime business and future convention business.

"This is the first week of the prime convention season," explained Austin Kenny, a spokesman for the Washington Convention and Visitors Association, who said 12 conventions of varying sizes are scheduled here this week, including Saturday's National Solidarity Day rally.

The National Automobile Dealers Association is now meeting at the Hyatt-Regency on Capitol Hill. Among the conventioneers due next week are the National Association of Business Economists, expected to fill 500 rooms at the Washington Hilton, and the Congressional Black Caucus Legislative Weekend, which has reserved another 1,500 rooms at the Washington Hilton.

City officials and the the Washington Convention and Visitors Association say they could not estimate the financial impact of a strike. Union officials contend that a strike would have a $1 million a day ripple effect.

Privately, officials for both sides said yesterday the chance of a citywide strike is now greater than it has been since 1946 -- the last time hotel workers walked off the job.

"It will all depend on what happens a few hours before midnight," one negotiator explained.

Because the last hotel strike here was 35 years ago, it is impossible to predict what might happen. When the hotel and restaurant union in San Franciso went on strike last year for 17 days, many chain hotels brought in management employes from other cities and hired unemployed workers to keep their hotels open.

At a press conference yesterday, Father Joaquin Bazan of Sacred Heart Gavan Center, at 16th Street and Park Road NW in the heart of the city's Hispanic community, said several unemployed members of his church had been approached by hotel officials to work in case of a strike. But he refused to name them or the hotels.

A group of community representatives, including several City Council members, sponsored the press conference and urged the hotel association to "begin serious good-faith bargaining" and discontinue what the Rev. John Steinbrook of Luther Place Church described as a "cold Marie Antoinette attitude."

City Council member David A. Clarke (D-Ward 1) said he will ask Mayor Marion Barry to open up Washington parks and public shelters if there is a strike so that union members coming to Saturday's national Solidarity Day rally will have a place to stay.

Council member John A. Wilson (D-Ward 2), chairman of the council's finance and revenue committee, warned that a strike would have a devastating effect on the city's economy and a special effect on poorer city residents.

Warren Graves, a special assistant to Barry, said the mayor, who is in Chicago en route to the Sugar Ray Leonard-Thomas Hearns fight Wednesday night in Las Vegas, says Barry has monitored the situation but has no plans at this point to get involved.

After seven hours of negotiations yesterday, negotiators had resolved only four issues, all of them considered minor by both sides. The most controversial of them would allow housekeepers an extra $10 for removing animal or human waste from hotel rooms. Thirty-five issues remained.

Spokesmen for both sides said no progress had been made Monday on the union's demand for a $32-a-week pay increase for each of three years and the association's counteroffer of less than $11 a week. Nor had the union and hotel owners agreed upon the union's demand for a new arbitration procedure, large emphasis on seniority and more pay for workers whose hotels cater to tour groups.

Rather than resolving those disputes, the union and association apparently became deadlocked on two other demands: a clause that would keep hotels from reducing any benefits now given workers but not outlined in their union contract, and a demand by the union that hotels help defray the cost of medical coverage for an employe's family.

Of the 9,600 members of Local 25, which is the largest local union in the District, about 6,000 are employed at the hotels now negotiating. Most of the union members earn less than $12,000 per year, about 52 percent of them are women, and 65 percent are blacks. Another third of the union members are Hispanic or members of other minority groups.

There are six hotels not participating in the negotiations -- The Shoreham, the Midtown Motor Inn, the Jefferson Hotel, Howard Johnson's Motor Lodge on Virginia Avenue NW and two of the five Holiday Inns in the city.