Members of the American Federation of Government Employees union gave their regards to Broadway today, snarling noontime Manhattan traffic (which didn't really need any help) in a protest march against the Reagan administration.

New Yorkers, who ordinarily are at home with demonstrations and strange dialects, puzzled over the meaning of the hundreds of signs carried by U.S. civil servants reading "RIF Reagan," "SSA Unfair to AFGE" and "AFGE Won't Take No More."

Because Congress is the board of directors, and the president their boss, federal workers have a difficult time explaining their labor problems to outsiders accustomed to less tolerant management.

When the federalese terms of RIF and SSA (Social Security Administration) were translated to a police patrolman named Incantalupo, for example, he looked at the crowd of noisy civil servants -- one woman was chanting "Reagan, RIF that sucker" -- smiled and said, "Youse is lucky he don't fire you. We did that, we'd get fired!"

Although the parade, which took approximately 500 delegates past attractions ranging from the Royal Shakespeare Company to On Stage, Snake Woman in Bondage, was orderly and festive, the intent was deadly serious.

Federal workers, ranging from some militants to Bible Belt conservatives, are angry and hurt by the treatment they have received since President Reagan took office.

One purpose of the AFGE convention is to let the public know that budget cuts mean service cuts, that civil servants are being used as scapegoats by politicians who blame the 2.8 million government employes for everything from inflation to unemployment.

The need to send that message is one reason Joe Russell of the Census Bureau in D.C. got unanimous convention agreement to interrupt today's nominating process for the midday march to 45th and Broadway.

In the afternoon, delegates returned to nominations for the 225,000-member AFL-CIO union's three top jobs.

Running for the top spot are incumbent president Ken Blaylock; his old adversary, Carl Sadler; national vice president Virgel Miller, and Douglas Cook.

Cook, from the Labor Department headquarters local and a last-minute candidate apparently got a big boost with delegates thanks to an excellent nominating speech from D.C. coworker Jay Edelson.

Late Wednesday, the 1,200-plus delegates will also fill the vacant job of executive vice president. Candidates are former AFGE staffer John Sturdivant; national vice presidents Ralph Fitch Jr., Roanoke; Allen Kaplan, Chicago; Walter F. Peters, California; Charles Carter, Colorado; and James H. Lynch Jr., Washington-based head of the union's overseas department. The other candidate is Robert Fletcher of Alabama, leader of a union local.

Nick Nolan, the union's secretary-treasurer, is being challenged for that by Bill Nussbaum of New York City and Norm Fischer, who works for the Air Force in Washington, D.C.

Most of the attention centers on the presidential race. Blaylock is basing much of the campaign on his reputation as a national spokesman for civil servants, earned as a member of the AFL-CIO executive board.

Sadler, who says he was robbed in the last election, calls for a return to the "Golden Age" of AFGE -- when he was head of the legislative department and the union and federal workers won big benefits from Congress and even had good relations with non-Democratic presidents like Richard Nixon.

Miller's supporters point to his long service and reputation for integrity.

Cook's last-minute campaign clearly hopes to capitalize on the fact that he is a new face in the union's complicated -- and sometimes very rough -- top leadership fights.