JESSE JACKSON is now playing at a whole new level of the game. He has moved from a symbolic candidacy in 1984, to a second-tier league unto himself in the early 1988 contests, to a solid second place in the overall race for the Democratic presidential nomination.
Mr. Jackson's share of delegates - while not likely to win him the Democratic nomination - will make it very difficult for anyone else to sew up the nomination by the end of primary-and-caucus season.
That would leave the leading candidates to barter among themselves over the nomination.
If Michael Dukakis and Albert Gore Jr. finish the season at all close in delegate count, ``then Jackson could give the nomination to either one,'' says William Galston of the Roosevelt Center for American Policy Studies.
What Jackson will want for his delegates has become a subject for rampant speculation with few clues from the candidate. The range of possibilities runs from a quiet accord with the future nominee that Jackson and blacks would have a voice in a Democratic presidency to a spot on the ticket for Jackson.
Most Democratic strategists doubt that Jackson will ask to be a running mate. They frankly hope not, and say they believe he knows he would doom the ticket in November.
There is no sign from the Jackson campaign or his allies that he has considered any goal but winning the presidency itself.
This remains unlikely. Jackson fulfilled the most optimistic expectations on Super Tuesday, winning four states and 370 delegates to Mr. Dukakis's 382 and Mr. Gore's 323. But this was also his big day of the season, because his base of black voters is most concentrated in the South.
Jackson's immediate future looks promising. His parting shot in the South comes in the South Carolina caucuses this Saturday, which he won in 1984 and should easily carry again. Next Tuesday, the election arrives in Illinois, Jackson's adopted home state.
Jackson is expected to do moderately well in Illinois, chiefly by carrying Chicago congressional districts. John S. Jackson, a political scientist at Southern Illinois University, sees Jackson finishing second to native-son Paul Simon in Illinois's ``beauty contest'' preference vote, but winning perhaps 15 to 18 of the 187 delegates at stake.
Mark Siegel, a consultant to the Democratic National Committee, sees Jackson winning big delegate chunks in Michigan, New York, Pennsylvania, California, and New Jersey. Potentially, he figures, Jackson could accumulate some 850 to 900 delegates of the 2,082 needed to nominate.
The importance of Jackson's showing, Mr. Siegel says, ``is that it's almost impossible for Dukakis to win the Democratic nomination on primaries and caucuses alone.''
If Dukakis wins about 50 percent of the remaining delegates, as Siegel predicts, and collects about half of the 685 uncommitted delegates, he would still be several hundred short of the nomination.
The most obvious scenario then has Dukakis offering Gore the running-mate spot. The ticket thus gains the nomination through Gore's delegates and a better shot at the presidency through Gore's now proved appeal to Southern moderates.
But Jackson could throw in some different options. If Gore has around 1,300 delegates, then Jackson's delegates could tip the nomination to either Gore or Dukakis.
What will Jackson want in return?
``Nobody knows,'' says Mr. Galston, Mondale's issues director in 1984. ``This is a man who makes things up on the run, who is infinitely flexible on strategy.''
Siegel says that any public deals struck with Jackson (or anyone else) would be disastrous for the Democrats. He expects that Jackson ``will accept on good faith a commitment by our nominee that Jesse Jackson and black Democrats will have a voice in a Democratic presidency.''
In the overall delegate tally, Dukakis leads with 455.5. Jackson follows with 393.55. Gore is third with 347.8. Richard Gephardt has dropped back sharply with 143.
Jackson finished first Tuesday in Louisiana, Mississippi, Georgia, and Virginia. Exit polls showed him performing significantly better among white voters than in 1984, but still well below 10 percent in most districts.
His widening base, analysts say, is another sign that his candidacy is coming of age. ``He's a player, he's earned it,'' Siegel says.