When Kenneth T. Blaylock took the floor at the AFL-CIO convention last year in Anaheim, Calif., he issued what some saw as a ringing challenge to the labor federation and to the Reagan administration -- and what others saw as an affront:

"When I look at Iran, I look at Vietnam, I look at Nicaragua, I look at El Salvador, Guatemala -- I would like for one time for my government to be on the side of the people, not on the side of rich dictators living behind high walls."

Not only was the speech in conflict with AFL-CIO tradition, it seemed at odds with the speaker's role as chief representative of the nation's government bureaucracy -- from Pentagon technicians and overseas embassy workers to Social Security clerks and Agriculture Department cattle inspectors.

But the emotional exchange that followed, culminating in a rebuke of Blaylock and other dissidents by AFL-CIO President Lane Kirkland, seems only to have strengthened Blaylock, president of the American Federation of Government Employees, in his opposition to military aid for the Salvadoran government and for the contras fighting Nicaragua's Sandinista regime.

Since Anaheim, he has spread his message widely, becoming what some unionists call labor's most vocal national spokesman against U.S. policy in Central America.

If that appears an unlikely role for Blaylock, president for 10 years of the largest civil service union, he does not acknowledge it.

"I believe that every union has a responsibility beyond the parochial needs of their members," he said in a recent interview. "The rank and file is telling the leadership something: Our government policy is wrong down there and we not only should oppose it, but we should be speaking out against it."

Blaylock, 51, has what labor activists call "bona fides." Born of Cherokee Indian blood near the reservation in North Carolina, he left home early and in 1954 found blue-collar civilian employment with the Air Force in Alabama.

"When I went to work at Maxwell Air Force Base in Montgomery as a plumber, there were two or three bad situations in the shop. And I got involved in those and went on to shop steward pretty quick." A progression of local, state and district offices followed. In 1976, Blaylock was elected AFGE national president in a convention runoff.

"I don't think many people really select the union movement as a career," he said. "You get involved and then people support you for your involvement, and you gain experience and a reputation."

Blaylock's reputation as a supporter of President Jimmy Carter's civil service revision almost cost him the union leadership in 1978, when the AFGE convention withdrew support for the measure. A recount gave Blaylock the victory by about 3,000 votes of more than 215,000 cast.

Some members of AFGE and rival federal unions still blame Blaylock for his key role in what became the 1978 Civil Service Reform Act. "His greatest accomplishment and his biggest mistake," said an AFGE local officer.

The law strengthened management's hand in some regards, but also codified federal labor-management policy, formerly under executive order. In light of President Reagan's first confrontation with federal labor -- the 1981 air traffic controllers strike -- some former critics now acknowledge that Blaylock was right.

"If we did not have the labor relations program in the federal sector locked into law, under this administration we'd be totally out of business," Blaylock said. The law also provided the ground for recent victories, including the union's right to receive employe home addresses, that may help stem AFGE's most pressing problem: declining membership.

AFGE's membership has dropped from almost 300,000 in the 1960s to about 180,000, although the union represents about 700,000 workers. AFGE lost roughly 1,000 members a month for several years under Blaylock, but a rejuvenated organizing effort has cut net monthly losses to about 400, he said.

Union finances reflect the decline. After several up-and-down years, AFGE ran in the red all four quarters of 1985, despite cutbacks. Convention delegates have been reluctant to raise dues because of the union's weakening position and a traditional anti-headquarters sentiment. They also have twice rejected Blaylock proposals to consolidate the union's 15 relatively autonomous districts.

Blaylock has survived other internal struggles, but with scars. A challenge to his 1980 reelection resulted in Labor Department monitoring of the 1982 rematch. A nine-week staff walkout three years ago was settled only after harsh strikebreaking threats. "We spent a lot of time talking about the staff and the 'company,' " said Gary DiNunno, a strike leader. "You don't hear that attitude anymore."

Last year, an administrative law judge recommended that Blaylock and two postal union presidents be suspended from federal employment for 60 days for violating Hatch Act restrictions on partisan political activity by government employes, specifically, for opposing Reagan and supporting Walter F. Mondale during the 1984 campaign. Blaylock said he is not sure what the penalty would mean if upheld; he has been on leave from his Air Force job for almost 20 years.

Gerald R. Ford in 1976 and Carter in 1980 also were targets of Blaylock attacks, based mainly on economic issues such as pay, on which federal unions have no bargaining rights. But the counteroffensive against the Reagan administration extends from bread-and-butter concerns to what Blaylock calls the "covert war" on federal employes, and the battle has been joined in the courts and other public forums as well as on Capitol Hill. Budget priorities and contracting-out are intended "to render the federal government dysfunctional and then to reduce it," Blaylock has told his members. Initiatives such as large-scale drug testing, polygraph exams and censorship use the "guise of national security" to "discredit, humiliate and quiet the federal work force."

Though the union's legislative record on pocketbook issues is mixed, Blaylock is generally seen as effective. "He's a really colorful witness in his down-home country way, and that's good," said Andrew A. Feinstein, staff director of the House civil service subcommittee.

"He speaks from the heart as well as the mind," said Jerry Klepner, former legislative director of the rival National Treasury Employees Union. "You don't have to cut through a lot of smoke to see the real Ken Blaylock."

Aides say that Blaylock's February 1985 trip to El Salvador and Nicaragua, where he met with local and U.S. officials, soldiers and insurgents, galvanized his activity on Latin America. "It didn't make me an expert," Blaylock said, "but I know what I saw."

Some labor sources, however, say Blaylock's stance is a risk, considering his union's diverse but generally conservative membership, concentrated in the Defense Department. They also note that programs of the AFL-CIO's International Affairs Department, a traditional supporter of U.S. policy, are heavily subsidized by the federal government and are linked to Social Democrats U.S.A., the strongly anticommunist remnant of the old Socialist Party.

Although Blaylock's convention speech last year -- he cited "shortcomings" in the federation's position -- broke an unwritten rule that banned such public debate, he said he has felt no retaliation. He does not consider himself "in any way a left-wing radical," he said. But if his positions align him with left-leaning unionists such as William Winpisinger of the Machinists and Ed Asner of the Screen Actors Guild, "that's great. That's the kind of company I want to be in."

Blaylock builds bridges where he can, whether with the Rev. Jesse L. Jackson's Rainbow Coalition or the National Labor Committee in Support of Democracy and Human Rights in Central America. His union recently contributed to the AFL-CIO's fund to help workers of La Prensa, the shuttered pro-contra Nicaraguan newspaper, even as Blaylock was criticizing, by implication, at least, the foreign policy stand of Kirkland.

"He's tough," said a unionist who accompanied Blaylock on the 1985 Latin America trip. "That's what makes Blaylock different in the labor movement. He's not scared of Lane; he's not scared of anybody. We need more of that in the union movement if we're ever going to prosper again."

BACKGROUND:

National president, American Federation of Government Employees; age 51. Civilian plumber, on leave from Maxwell Air Force Base, Ala. Former AFGE district vice president for southern region, other union offices. Vice president, former president, AFL-CIO Public Employee Department. Executive council member, AFL-CIO.