There was faint hope after the 1982 city elections that labor leaders who were bitterly divided over the Democratic primary race for mayor would set aside their differences and reunite.

Officials of the major public employe unions, who gained the upper hand by backing Mayor Marion Barry's successful reelection campaign, quietly began patching things up with some of the labor bosses in the building trades and the food-service industry who supported Patricia Roberts Harris in the Democratic primary.

But this move toward reconciliation now appears threatened by a mushrooming controversy within labor's ranks over recently enacted changes in the District's unemployment compensation law--changes that reduced benefits for the average worker.

Ron Richardson, secretary-treasurer of Local 25 of the Hotel and Restaurant Employees Union, and other officials of Food and Allied Service Trades Council (FAST) have launched an initiative drive to try to overturn the new legislation and restore the cuts.

This puts them at odds with the leadership of the Metropolitan Washington Council (AFL-CIO), an umbrella group of about 145 area unions, which reluctantly endorsed the legislation as the least painful way to deal with a $57 million deficit in the city's unemployment compensation fund.

While Richardson doesn't speak for labor in Washington (in fact, his 95,000-member local was suspended by the labor council last year in a dispute over the payment of dues), his crusade against the new law is beginning to strike a responsive chord.

The law, proposed by the mayor and strongly favored by the Greater Washington Board of Trade, reduced the maximum number of weeks that unemployed workers can collect city unemployment benefits from 34 to 26 weeks and eliminated benefits for persons fired from their jobs for cause.

It's no secret that many members of the labor council's executive board held their noses when they voted to go along with the recommendation of Joslyn N. Williams, the labor council president, to endorse the legislation.

Moreover, some labor leaders were miffed Williams either didn't receive sufficient advance warning from the mayor's office or else waited too long to provide them with the details of the mayor's proposal--a measure that sailed through the City Council early this year and went into effect March 17.

Williams said he did the best he could to keep other labor leaders informed of the fast-moving negotiations with the mayor's office and City Council members.

"The proposals were constantly changing each day," he said. "We dealt with the situation as best we could. . . . We do not like the bill, but we think it is the best one we could get under the circumstances."

Washington voters could be treated this fall to the bizarre spectacle of the labor council teaming up with the Board of Trade to try to crush an initiative campaign of dissident labor unions.

Assuming that Richardson's group succeeds in gathering enough signatures to put a measure on the ballot, some members of the labor council who reluctantly endorsed the legislation last winter may find it extremely difficult to publicly endorse the reduction in benefits in the heat of a fall campaign.

"Ron is opening a Pandora's box with all of this," said a spokesman for the labor council. "There's no question about the divisive nature of it."

A high-ranking labor official, sympathetic to Richardson but who plans to stand behind the labor council's position, conceded "there has been quite a bit of talk" about the initiative among local union members.

City Council chairman David A. Clarke said recently he didn't object to the initiative drive, provided the labor organizers come up with a new plan that will leave the unemployment fund solvent. "I don't think they can," Clarke said.

Clarke's point hasn't been lost on a lot of labor leaders who are nominally sympathetic to Richardson's effort but who doubt they could come up with a better solution to the rising deficit in the unemployment compensation fund without extensive study.

A new nine-member panel representing government, business and labor was appointed last week to consider alternatives to the new law, which will expire in 1985. However, no representative of the groups seeking the initiative was included.

Labor council officials say it is a mistake to portray the current flap over unemployment compensation as a rift within organized labor. Rather, they say, it is the latest chapter in a long-standing feud between Richardson, a savvy and ambitious strategist, and the labor council, which has become dominated by his rivals in the public employe unions.

Some suggest Richardson is pushing the initiative drive to "demagogue" on unemployment compensation and to drum up support for his effort to win election this June to another three-year term as secretary-treasurer of Local 25.

But Richardson said he's not worried about winning reelection. His real concern, he said, is that the labor council's leadership has grown lethargic and conservative--more interested in currying favor with the mayor and the local establishment than in fighting for the benefits of rank-and-file members.

"In any state in the country, unemployment and worker's compensation are the two gut political issues of any labor organization," Richardson said recently. "But here it seems it's more important for labor leaders to be invited to the right parties than to worry about workers' benefits."