Perhaps it is in the nature of the season, but we now have the second coming of Gary Hart. But while the overnight polls are telling us that Hart may once again be a viable candidate, very little has been heard in the media about front-runner Jesse Jackson, prompting some people to say there's a conspiracy on the part of the media and the Democratic leaders to ignore him.

Many years ago, author Ralph Ellison wrote a book titled "Invisible Man." Now we have the most incredible phenomenon of all, an invisible presidential candidate.

Jackson rose to the top of the polls seven months ago, after Hart's presidential aspirations were killed by his springtime spree with Miami model Donna Rice, his admissions of unfaithfulness and other stories about his womanizing.

On the heels of Hart's sudden departure, Jackson's escalation to front-runner status took everyone by surprise, and the descriptions of his status were qualified in a number of ways. He was called the "nominal front-runner" and "the temporary front-runner."

So far, however, he has not been ignored by the polls prior to Hart's reentry into the race that continue to place him at the head of the six Democratic presidential contenders. But as Jackson continued to maintain his front-runner status in later polls and to perform well in the debates, as he made staff changes to tighten his organization and professionalize his campaign, the characterizations of him changed little.

After nearly seven months as front-runner, many news and wire stories still refer to Jackson by tossing in the caveat that there is "a widespread view" that "the black civil rights activist will not win the nomination."

The assumption about Jackson seems to be that no matter how well he does at the polls, he can never win the nomination. And the characterization of him as a black civil rights activist severely limits his constituency. For Jackson is more than a black candidate; he would be more aptly termed the protest candidate, the antiestablishment figure whose Rainbow Coalition is much more of a reality in 1988 than it was in 1984. Such a characterization also carries a predetermined kind of judgment without regard for the fact that so far, nobody seems to be able to undermine him or take the lead.

In spite of Jackson's performance in the debates, he is still treated almost as if he didn't exist, as a nonentity. It makes you wonder if Jackson got out of the race and then got back in whether anybody would do an overnight poll to see how he would fare against other Democrats in the field.

And it's not only the media that have subtly made Jackson a nonstory. His fellow Democrats also have repeatedly said publicly that he could never be nominated. In fact, the statements are so common that some Democratic insiders are bothered by the trend.

"It's disturbing that Democrats would make such a judgment in public, especially given the performance of Hart in 1984," says Sharon Pratt Dixon, treasurer of the Democratic National Committee. "Hart was the protest candidate then, and he almost upset Mondale. In 1988, he was considered the front-runner. But Jackson in the current, present campaign was never seriously considered although he continued to get standing and performed well in the debates."

It would be unfair and simplistic, even racist, for me to say that Jackson is the invisible presidential candidate only because he is a black man. Many other factors are being taken into consideration.

For example, Jackson's support is in the 20 percent range and national polls at this stage chiefly measure voter recognition of candidates' names. Broader support is reflected in the 30 percent range, a point Hart reached but that Jackson so far has not. Moreover, Jackson has not made great strides in Iowa and New Hampshire, and a formidable contender must win those primaries or get delegates in those states. To the extent that he is failing to do that, it is legitimate to note the uncertainty of his chances.

But why not unequivocally refer to him as the front-runner and then point out parenthetically the negative ratings with which he continues to be plagued? That's the way Sen. Edward M. Kennedy's prospective candidacy was handled. He was considered a legitimate contender but was parenthetically tagged with negative ratings because of Chappaquiddick.

It's axiomatic that any candidate plagued by a number of negatives will have difficulty winning the election. But by saying he is not expected to win -- thereby failing to legitimize the candidacy -- the characterization can become a self-fulfilling prophecy.

And when a man -- or a presidential candidate -- is invisible, that does a disservice not only to him, but also to our democracy.