Pat Harris for mayor? Would the former Carter administration Cabinet officer, a woman who has resided at the highest levels of power, really want to spend four years being responsible for Washington's traffic lights and garbage trucks? Absurd, some say. Why, just ask Pat Harris.

Except that when you ask Patricia Roberts Harris about this preposterous long-running rumor, she says that as far as she's concerned, it's not so preposterous at all.

"I have made no decision," Harris said recently. "Several of my friends -- I know this sounds like a cliche, but several people have asked me to give them time to persuade me to run. I suppose it is significant that I have not told them that I would not run." Those seem the careful words of someone who has given the matter considerable thought.

A Harris candidacy would suggest an obvious parallel with the recent mayoral election in Atlanta, where another Carter administration refugee, former UN ambassador Andrew Young, ran for mayor and won. One of the major campaign issues was whether Young, after a heady taste of life in the global fast lane, was truly interested in the rather more prosaic duties of being a big-city mayor. Garbage, street repair, water bills, traffic lights -- a far cry from war, peace and detente.

But Harris has a ready answer. She points out that while Young was involved with international politics, the two Cabinet posts she held under Carter -- a stint as secretary of Housing and Urban Development and another as secretary of Health and Human Services -- are more involved with the realities of urban life in America.

"I've really never been away from the concerns of the cities," she said. "That's what I spent four years doing. I would say that the parallels with Andy are just not there. . . . I said years and years ago, when I was president of my civic association, that a lot more people are impacted by whether their traffic light works than whether we have a Peace Corps."

But while Harris sits in her upper Northwest Washington home, "taking a year off" and flirting with the idea of running for mayor, there are political realities that any candidate for mayor has to face. Other probable contenders are busy locking up money and support, to say nothing of incumbent Mayor Marion Barry. One potential candidate, Betty Ann Kane, plans to announce the formation of an exploratory committee within the next few days. Time's a-wastin'.

By all accounts, there is one prime mover behind the Pat-Harris-for-Mayor prospective boomlet: Robert B. Washington Jr., the former chairman of the D.C. Democratic Party.

Washington has been making the political rounds in recent weeks, telling everyone not to count Harris out and meanwhile trying to convince Harris to count herself in. He brings some clout to the notion, but some observers believe he doesn't bring enough firepower to get Harris elected.

The theory is that Harris would bring proven administrative competence, as a result of her Cabinet-level service, to the mayor's office. She has been a longtime Washington resident, and thus is familiar with the city and its problems. In addition, her national visibility could bring added prestige to the District Building, the reasoning goes.

One prominent lawyer familiar with the effort on Harris' behalf said that it begins with the premise that Barry is politically weak -- "they smell blood," was the way he put it. But most of the money for a Harris campaign would likely have to be raised from out of town, the lawyer speculated, since local contributors are already being leaned on by other prospective candidates.

A local party official said that although Harris' name is well-known nationally and in well-heeled black circles here, she still would have a long way to go toward developing the kind of citywide base needed to win. "Bob Washington is a superb politician, no question about that, but he always concentrates on money and things like that and forgets the grass roots," the official said. "You can't do that in Washington."

Another potential problem would be that there already are several others interested in running from the same political base among well-off blacks that Harris comes from. These include former City Council chairman Sterling Tucker, Council Chairman Arrington Dixon and Council member Charlene Drew Jarvis, all of whom have had meetings on making a run for the corner office on the top floor of the District Building. Someone would have to pull out, and Harris would be a relative latecomer to this jam-packed field.

Harris, meanwhile, says she hasn't even reached the hard political truths. She says she is in no hurry to make a decision, although some sources are convinced she must move within the next month or so. There is talk -- nothing definite, yet -- of an upcoming poll to gauge whatever support for her might be out there.

Harris seems to relish the courtship. She reminds a reporter that she has won citywide office in Washington before -- she was elected Democratic National Committeewoman, "and you run for that just like you run for mayor."

Well, not quite. And she knows it. But it's not always easy to say no.