"I'm a political hack,"says Ivanhoe Donaldson, generally considered the alter ego of Mayor-elect Marion Barry. "He's a politican.

But if Donaldson is the late '70s model of the city hall hack, the breed has changed quite a bit since the days of blue-suited satchel-fannied politicos with 25-cent shoeshine. Donaldson, who will serve after the Jan. 2 inauguration as general assistant and "staff honcho" to the Mayor, is an intense 32-year-old with the build of a long-distance runner and a mind that can leap from questions of staff organisation to the music of John Coltrane, the paintings of Charles White and the writings of Dostoevsky, Camus and Margaret Walker.

Aesthetic conversation has not been in demand lately in the bare beige office on the third floor of the National Theater Building which serves as Barry's transition headquarters. What Donaldson has brought to his work there, associates say, is what he brought to his role as manager of Barry's long-shot mayoral campaign-energy, a taste for power, a sense of urgency about Barry's priorities and a proclivity for hard work.

"I'm a workaholic," Donaldson says cheerfully.

The two men met when both were organizers for the Student Non-Violent Coordinating Committee in the '60s. As the civil rights movement waned. Donaldson moved into electoral politics, supporting candidates like Julian Bond and Andrew Young. He managed Barry's campaign for City Council in 1974.

But Donaldson says he has never been tempted to run for office himself.

As a candidate, "You have to show some sense that everybody's important. I can believe that, but I don't have to operate that way. Besides, some folks are designed to work for other people and others are designed to be out front."

Out front, it seems, is not where Donaldson prefers to be. "The media can make you into a personality, instead of someone who has a job to do," he fretted. "But I assume it's a passing fancy. In another two months the media will have a shiny crop of new faces to write about, and I'll be able to concentrate on what I'm trying to do."

What he wants to do, he says, is what Marion Barry wants to do - an ambitious list including, but not limited to, giving new hope to the District's young people, making municipal government responsive and helping low-income people stay in their homes despite mounting housing costs.

Donaldson's devotion to hard work and long hours detracts from the amount of time he can spend with his wife of nine months, Winifred Burrell Donaldson, administrative assistant to Rep. Andrew Jacobs Jr. (D-Ind.). "But she understands the world of politics - plus she's very supportive of Marion Barry and what I'm trying to do," he says.

Behind his obsession with politics is a set of aims slightly different from those of the average "political junkie" - the same goals that led him and hundreds of others to risk their lives repeatedly in the civil rights movement in the South. At the end of a lifetime, Donaldson says, "You'd like to feel that you did what was right, that you didn't compromise yourself, that you didn't see injustice and not respond to it.

"I want to participate in creating a more humane society. I know that future generations are going to go through their own struggles, and I know that history is cyclical in some senses. But I'd like to know that generations in the 21st century won't have to go through what my father and I went through." CAPTION: Picture 1 and 2, no caption, Photographs by Bill Snead