Will Jesse Jackson once again run for president of the United States? Probably.

And what would be the benefit -- for himself or for his frustrated constituency -- of a second run? I don't know, and it's a fair guess that Jackson doesn't know either.

So why is he thinking of doing it? Well, what else is there for him to do that comes close to drawing on his rich blend of leadership, oratorical brilliance, personal charm, insight and hunger for the limelight?

Jesse Jackson is, as his crowd-priming chant has it, "somebody . . . black, beautiful and proud." But just what is he? What does he want to be? His inability to come up with an answer, or for his considerable following to provide the answer for him, may be the chief reason he wants to run for president.

If he wanted to be president, and if he thought he had a reasonable chance of making it, he might still be doing some of the things he has become famous for: spreading his message of hope for the frustrated, trying to lift the morals (as well as the ambitions) of the black underclass, struggling to save the young ones especially from dope, promiscuity, academic indifference and other manifestations of their deep despair.

He might also be doing some things very differently: running in winnable political contests, garnering the respect and support of his political peers, learning policy formation and governance and coalition building from the inside, climbing the political ladder. He would, in short, be building the basis for a realistic shot at the world's premier political job, knowing that even if he fell short, he would still be a powerful political presence.

But knowing that he can't be president, and unable to decide what else he wants to be, he overtaxes himself and his credibility trying to be everything: country preacher, policy analyst, party builder, populist, educator, ethicist, economic radical, moral conservative, redistributor of wealth and power, diplomatic trouble-shooter and the national conscience.

Since he cannot convince enough Americans -- even among his admirers -- that he can be all these things, he comes off as little more than a headline grabber.

Which is too bad. Jackson, for all his flamboyance and sophomorisms, possesses gifts of intelligence and insight almost unequalled on the American scene. He may, in fact, be a victim of too many gifts.

If all he could do was teach, he might be an uncommonly successful principal or school administrator. If he were only a preacher, he might be the country's foremost religious leader. If he were merely a diplomat, he might, given his ability to see through the rhetoric and grasp the fundamental, be an extraordinarily valuable mediator.

But he is all these things, and (despite his undeniable personal flaws) many more; and no single role is capable of containing him or keeping his interest for long.

For a time, he was driven by the ambition to be the successor to his hero Martin Luther King Jr., as America's No. 1 civil rights leader. But he achieved that goal, only to discover that civil rights leadership wasn't what it used to be.

So what does he want to be now? What will be the solid base from which he will make his forays into the myriad controversies that, for a time, attract his interest? It used to be his Chicago-based Operation PUSH, but he has outgrown that, as he has outgrown virtually every mantle he has assumed.

If he becomes a presidential candidate once again, whether as a Democrat or as the standard bearer of his Rainbow Coalition, it will be less for the hope of winning office or influencing policy than for the want of anything else to do.

And it will be a distraction, a waste and in some ways a tragedy.

Running for president is a wonderful ego trip, but it's a damned poor profession.