The talk is of a black candidate for the Democratic presidential nomination. But who are the people picking the candidate, and can they be trusted not to pick Jesse Jackson?

There are two ways to think about a black candidacy. First, what does it do to help galvanize minority voter participation? Second, what does it do toward building a black policy consensus and selling it to the inevitable white victor? (These two ends are well worth pursuing even though the Democrats aren't about to nominate a black.)

Choosing Jesse Jackson could do a lot to make the endeavor look like nothing more than a voter registration campaign, and I don't think that's what's needed from a black candidacy.

It didn't take Harold Washington's candidacy in Chicago to enlist an army of newly registered voters. It was Jane Byrne's careless administration, plus able local leadership (including that of Jesse Jackson) that did it. Anti-Reagan sentiment is more than ample to fuel a similar nationwide drive. There can and should be one.

But a voter registration effort might be hampered if it were centered on an individual candidate. Money to finance it would be harder to raise, especially from whites and institutional sources. Many national and local leaders would be hesitant to lend their earnest support-- whether because of substantive differences with the candidate or simple jealousy. So the wrong candidate could undermine the potential electoral influence of blacks, generally and within the Democratic Party.

But consider a black candidacy aimed not just at boosting voter registration but at setting a black agenda. Campaigns do create demands for speeches, responses to press queries, negotiations with groups, and opinion polls. That means modest demands for ideas, or at least positions. A candidate trying to create and motivate a black and Hispanic constituency would take care to base his or her views on the needs and preferences of minorities, if the candidate were a good politician.

Is Jesse Jackson a good politician, or merely a charismatic leader, skilled in guerrilla warfare but ill-suited to the campaign tasks of alliance and management? Because I favor a campaign, not a crusade, I doubt that Jesse Jackson is the right pick this year. Unless another person submits to a draft--Andrew Young, Vernon Jordan, Maynard Jackson--the people who are thinking about choosing a candidate should postpone a candidacy until 1988.

Which brings up the question of just who the people are who will be making such decisions. Since there is no national black political machine or policy-setting mechanism, there's more than a small problem of legitimacy here. That must be one reason why Jackson has hesitated before declaring his candidacy. Perhaps he senses the need to be able to claim that he is, at least, the candidate of, by and for the smoke-filled room.

But the strategists are stymied by the legitimacy problem too. Sure, some of them have won local elections. Others have been tapped to run important civil rights organizations, usually by boards of directors made up of veteran, unelected advocates of black advancement. This is certainly a legitimacy of sorts. But it's a kind of benevolent oligarchy quite different from our familiar democratic norms.

So what? I urge the smokers to chomp on their cigars and press ahead. They should act the parts in which they're cast, because blacks have no alternative. Make the risky decisions now, not after the moment has passed. Those in the smoke-filled room would do a disservice if they husbanded their influence in order to preserve leadership status by avoiding defeats.

And even if they decide against a black candidacy in 1984, neither agenda-setting nor voter participation has to wait. Groups of black academics, notable and otherwise, have been meeting for months with a newfound determination to formulate a manifesto. The assembled leaders of major black organizations have already given tentative endorsement to one draft, which should be released shortly. Will it break new ground on education, crime and fatherless households?

True, a black platform, like the decision on a candidate, will have a problem of legitimacy. There's been no issues convention or even adoption by an attractive black candidate. There are only the self-appointed intellectuals trying to serve by being influential.

But like the risky political decision, an idea will gain legitimacy by attracting adherents.

There's plenty of reason to worry about the workings of smoke-filled rooms. But it is the only political process blacks have now.