More than 75 percent of the D.C. public school system's 2,500 cafeteria workers, bus drivers, janitors and service employes -- dissatisfied with school management and with their present labor union -- have signed cards petitioning to join the International Brotherhood of Teamsters.

The Teamsters, who last August won an election to represent 2,400 District prison and jail employes, are battling the incumbent union, the American Federation of State, County and Municipal Employees (AFSCME) in a costly election campaign fought with telephone banks, direct-mail mudslinging and slick ads.

The Teamster inroads into Washington's city government illustrate the union's strong appeal to many blue-collar workers, including those in government, despite an image of corruption and criminality that has plagued the nation's biggest labor union, according to labor management experts.

"Their reputation for tougher bargaining most likely has made them more attractive, especially in places where people have had problems with management," said Donald H. Weinberg, D.C. government director of labor relations. "Whatever problems Teamsters may have with corruption are at the national level, and unless it hits at the local level, it doesn't have the same impact, if the local people are straight."

The Teamsters union -- whose 1.6 million membership includes more than 150,000 city, county and state workers -- was set back by last month's indictment of its president, Jackie Presser, the fourth Teamster chief of the last five to face criminal charges while in office. Presser was overwhelmingly reelected at the union convention in Las Vegas, five days after his indictment on charges of embezzlement and racketeering.

Teamster officials acknowledge that the criminal charges deter some workers from wanting to join the union. But they said many workers consider it a secondary issue to whether the union can deliver better pay and benefits. In some cases, they add, workers believe that the unsavory image is actually beneficial because it may frighten management.

"Every now and then Jackie Presser comes up as an issue, but it's only once in a while. When you have been screwed around by management for 20 years, and didn't get help from your union, that's the real issue" that attracts people to the Teamsters, said Phillip Feaster, president of Teamster Local 639, whose 5,500 members are mostly truckers and warehouse workers for Safeway, Giant Food and United Parcel Service. Local 639 is now running the D.C. school campaign, with the help of a $12,000-a-month grant from Presser and the loan of Teamster organizers.

"We are the biggest and the strongest union . . . and I am not scared of Mayor Marion Barry," said Feaster, 47, a tough-talking former truck driver from North Carolina. He said the Teamsters' primary appeal to school workers is that a tough union will provide them a stronger voice than AFSCME in dealing with management on issues of understaffing, discipline, cuts in work hours, and loss of benefits that many have experienced.

AFSCME has represented D.C. employes for 20 years, and the Teamsters have tried to portray that organization as too cozy with the Barry administration and too disorganized to provide strong representation. That same pitch was successful last August when the Teamsters defeated the American Federation of Government Employees, which had represented prison workers for 20 years.

The school workers' mail-ballot election ends this week, with votes tallied on Monday.

AFSCME officials contend that the Teamsters' tough image is overrated, that they cannot necessarily deliver any better pay or benefits, and that workers are being misled into believing the larger union will pay more attention to their local problems.

AFSCME's national headquarters took over the anti-Teamster campaign and has spent about $100,000, hiring a firm to conduct polling among workers and to make telephone appeals, according to union spokesman Phil Sparks.

Joslyn Williams, president of the 150,000-member Metropolitan Washington Council, AFL-CIO, has campaigned for AFSCME, an AFL-CIO union, and "raised questions about the integrity of the Teamsters" in speeches and mailings to union members, he said.

AFSCME mailings have told workers: "The Teamsters Talk Trash by the Truckload . . . . Don't Buy the Teamsters' Trash." But AFSCME has not specifically raised the corruption issue in its campaign, officials said.

The Teamsters, which originated in 1903 as a union of horse- and mule-team drivers, has been strongest in trucking. But less than one-quarter of its members now are truckers, as the union has diversified. Minnesota social workers, Oregon psychologists, Illinois police officers and Detroit speech therapists are among the public-sector workers who now belong to it.

"The Teamsters are seeking to move into the public sector essentially to clean up their image" by signing up government workers, said William Lucy, the secretary-treasurer of AFSCME, which has 1 million members and is the largest public-sector union. "Their victory in D.C. Corrections has whetted their appetite."

Lucy, AFSCME's second-ranking national officer and a close ally of Barry, said that some workers are wrongly taking out frustrations on AFSCME because of chronic problems of school system funding. "We have made tremendous gains. We were representing these employes when they had no grievance procedures, no negotiations over wages and benefits . . . , " he said.

School service employes, whose salaries range from $4 to $14 an hour, have been disgruntled because of several cutbacks, including a reduction in daily work hours for food service workers and the loss of unemployment benefits that they formerly collected during summer vacation, setbacks that AFSCME said it is fighting.

In recent interviews, pro-Teamster school workers said they believe the new union would be their best bet. "If the Teamsters are so corrupt, then explain to me why every time you pick up the paper you find people in D.C. government are more corrupt," said Floyd Johnson, 42, a 10-year school employe. "I think people just want to give the Teamsters a bad name because they are getting too powerful."

"I was a Teamster when I worked at Safeway and I got better representation than I am getting now," said Melvin Allison, 56, a school warehouse worker who was a major organizer of the Teamster effort.

Allison said he approached the Teamsters last year because he and fellow workers are overworked, are refused "light duty" assignments after they suffer injuries, and are frequently disciplined.

Kenneth Nickoles, the school system's director of labor relations, said, "There are a number of dissatisfied workers," but added that he believed grievances have not been that numerous.

If the Teamsters win next week, said Barry Feinstein, director of Teamster public employe organizing, "then piece by piece, we are going to organize the entire D.C. government."