A substantial number of the Senate's restaurant workers has organized to demand the collective bargaining rights Congress has approved for other Americans, but withholds from many of its own employes.

The nearly year-long campaign by the Capitol Employes Organizing Group has turned the normally sedate-to-boring Senate dining areas into labor-management battlegrounds. But, more than that, it has raised anew the question of whether Congress has the right to exempt itself from the laws it requires others to live by.

Sixty percent of the 220 Senate food service workers have signed cards saying they want an independent union, according to CEOG leaders and Senate dining supervisors. The workers say they want the Senate to draft and approve a resolution giving them the right to bargain for wages, benefits, hours and working conditions.

Congress has allowed employes of the Government Printing Office and the Library of Congress to organize, but not the Senate's food service workers.

These employes are mostly black and semi-skilled, members of what Jay Treadwell, director of the Senate's 13-unit food service operation, calls a "self-perpetuating work force" drawn largely from area families that have worked in Hill service jobs down through the years.

That work-force profile often has led to the belief that the restaurant and other congressional service employes are enslaved on "the last plantation." The restaurant workers often refer to themselves as "field hands" (those employed in the less prestigious eateries of the Russell and Dirksen office buildings) and "house niggers" (those employed in the more prestigious Senate restaurants in the Capitol).

The "field hands" are pushing hardest for the union.

"It really angers me when people use those 'plantation' references," Treadwell said. He said the Senate food-service workers are paid an average of $4.16 hourly, "comparable to or better than that paid in other Washington area restaurants."

The workers also receive health benefits, free uniforms and free meals (breakfast and lunch on a regular workday), according to other restaurant supervisors.

But "we don't have any protection the way it is now," said Ruth Bennett, 49, whose job "is to make sure all of the salads go out to the right restaurants." She said the food-service managers "can hire and fire anyone they choose. They make their own rules as they go along. If we had a union, maybe we could all sit down and make the rules together."

"Yes, I do have the power to hire and fire. I can fire them without any reason whatsoever," Treadwell said.

"But, I've never fired anyone without cause. Besides, I have 100 appellate individuals, 100 bosses, who can veto any firing," he said, referring to the senators.

Treadwell said he has "worked hard to boost the morale" of the restaurant workers. But he said "there is no way" he can give them what the majority apparently wants -- a union.

"I work for the architect of the Capitol, who works for the Senate and the Senate Rules Committee, which has jusrisdiction over the Senate dining rooms.I'm not opposed to the union, but, under the law, I have no authority to recognize one," he said.

William Raines, chief assistant to Architect George M. White, said the same thing. "The law [the National Labor Relations Act of 1935] does not apply to members of Congress. . . . This office exists as the pleasure of Congress. It cannot change the law," he said. Moreover, the office of the Capitol architect disputes the organizers' connection that a majority of the food service workers would be willing to join a union.

Still, inquires to the Senate Rules Committee about the organizing drive frequently are redirected to the Capitol architect's office.

"I'm aware of the situation [the union campaign], but the architect of the Capitol is responsible for running the Senate dining rooms," said William McWhorter Cochrane, Rules Committee staff director.

"The matter is not before the committee right now, and it's best that one unit, the architect, deal with it," Cochrane said.

The architect's office has stopped taking telephone calls from CEOG organizer Stuart Smith, a Justice Department employe who said he is running the union campaign on his own time. The office also ignores all CEOG written notices, according to a Captiol administrator, who explained: Since we have no authority to deal with a union, it makes little sense to talk to an organization that calls itself one."

"It's the old runaround," Smith said. "These senators are always talking about the working man. They even get up and praise Polish workers for demanding free trade union rights from a communist government. But they don't want anybody poking around in their own backyard.

"It seems that everybody's a liberal until it comes to his own maids and cooks."

CEOG members say they have appealed to a number of senators to consider their request, mostly in vain.

"Those people upstairs in the Senate don't want to listen to us because they think we are a bunch of flunkies," said Henry Manning, a restaurant worker and CEOG activist. "The staff people in a lot of those offices look down on us. . . . They tell us that they will talk to the senators, but they never get back to us."

Manning said the only staff to show any interest in CEOG was that of Sen. Edward M. Kennedy (D-Mass.). But Kennedy staffers reached by The Washington Post said they had never heard of the organization.

Smith said the Senate "can easily do" for its food-service workers what Congress has done for employes in the Library of Congress and the Government Printing Office. Both of those units are part of the legislative branch and both, under Title VII of the 1978 Civil Service Reform Act, have collective bargaining rights.

The Library has five collective bargaining units and the printing office, which was given the right to "confer" with Congress on wages in the Keiss Act of 1924, has 17 bargaining units in Washington, and five elsewhere in the country.

But neither library nor printing office workers are considered the direct employes of Congress, even though they work for legislative branch agencies.

"There is a difference in the law, and that difference does not apply [favorably] to congressional employes," said a ranking Senate source who requested anonymity.

"Congressional staffers and cafeteria workers are in the same boat on this one. If you unionize one, you'll have to unionize the other, and neither the Senate nor the House will go along with that," the source said.