Exhilarated by the Democratic primary victory of Harold Washington in Chicago--and angered by front-runner Walter Mondale's endorsement of another candidate--several black political leaders are thinking about running a black presidential candidate in the Democratic primaries next year. It's a bad idea, and for more than the obvious reason that it's not likely to be successful.

Washington, after all, won just 36 percent of the vote from an electorate that was 40 percent black. The national Democratic primary electorate will be no more than 20 percent black, even if the most optimistic predictions about black voter registration drives turn out to be true. A candidate seeking support from black voters only, as Washington did, will get only a fraction of the black vote; many black voters will prefer, in Rep. Mickey Leland's words, "a person who might win" to a person who is "running to barter."

As a general strategy, it makes little sense in a majority-white nation to run candidacies aimed at black voters alone. Black candidates have already made the gains possible through such a strategy, some of them long ago. It's hard to understand why the victory of Washington--who has spent time in jail--was so exciting when you consider that Cleveland and Gary elected black mayors with considerably more attractive credentials 16 years ago, in 1967, and Detroit and mostly white Los Angeles did so in 1973.

It's simply not possible to draw many more black-majority congressional and state legislative districts than have already been created by sympathetic legislatures or enforcers of the Voting Rights Act. Larger numbers of blacks in office will come not through Harold Washington's strategy of appealing to black voters only but through Thomas Bradley's strategy of appealing to voters regardless of race. Anyway, black voters don't always want to get ride of white officeholders; otherwise Baltimore's black majority would have ousted Mayor William Donald Schaefer years ago.

The real question is whether black voters can work effectively through the political system to get things they want. A black presidential candidacy, aimed totally at blacks, would be a diversion from that purpose.

But, say the advocates of such a candidacy, amassing a bloc of 10 percent of the Democratic delegates would give us bargaining power.

Let's assume the unlikely: that the convention would be deadlocked between the candidates, and that those 10 percent would act as a unit; in that case, what can they bargain for? Platform planks? A chance to deliver a speech from the podium? Commitments to advocate such-and-such policies once in office?

No one with much sense will put in all the effort even a token presidential campaign requires for such insubstantial returns.

A black candidacy has one advantage for some black leaders: it obscures the fact that they are not sure what they want. Like most leaders who have been brilliantly successful in achieving a set of specific goals, they are unsure of what to do next. Legal segregation is dead, discrimination in jobs and public accommodations is vastly reduced, blacks are now visibly involved in the highest reaches of public life and are rising rapidly in the professions and business.

Yet no sensible American believes that blacks do not suffer from serious handicaps due to present or past discrimination. What are those handicaps? What can society and government do to fix them? Answering those questions, providing goals that are both farsighted and achievable-- these are the difficult tasks facing national black leaders.

The standard answers--what you would probably hear a black presidential candidate bargaining for--are not terribly helpful. Some may argue for a massive public jobs program or for a high guaranteed annual income. But the guaranteed income idea was rejected pretty conclusively a decade ago, when it had a lot of support. Now we are less sure we can afford such an expensive solution, and less certain that it would not promote the kind of dependency on welfare and the high unemployment that are severe problems for many blacks.

As for jobs programs, even in a deep recession, most voters seem skeptical that they are anything more than makework. If unemployment falls, the impetus for such programs will vanish.

President Reagan in his State of the Union message called for a stronger enforcement of fair housing laws. National black leaders are quietly exploring the possibility that a strong fair housing law, like the bill that passed the House in 1980, could win administration support and be passed by this Congress. This is a constructive effort that could help a lot of black people achieve what they want in life and help end a persistent form of racial discrimination. A black presidential candidacy might divert the efforts of many talented black leaders and the attention of thousands of politically active blacks from this cause.

Finally, advocates of a black presidential candidacy argue that having all white candidates "perpetuates the myth of white superiority and black inferiority." But isn't that myth more likely to be perpetuated when a black candidate seeking primarily black votes admits he is not serious about becoming president? Let's wait for a black candidate who genuinely wants to be president and is able to persuade others he is a genuine candidate.

It may not take as long as some think. Politicians of national stature do not emerge in precise proportion to ethnic or racial percentages: Edmund Muskie came along before any Italian- American presidential candidate, even though there are more Americans of Italian than of Polish descent; Edward Brooke was elected in a state 96 percent white.

There are many brilliant young blacks, interested in public affairs, who are now obtaining a wide range of experience; it is easy to imagine them developing, as Tom Bradley and others have, wide appeal to white as well as black voters. In the meantime, a black political candidacy is a dead end, a cul-de-sac, a way to escape rather than confront persistent and difficult problems.