The long black limousine glided to a stop outside the Waldorf Astoria Hotel and in a matter of milliseconds the sidewalk became a scrambling, snarling swarm of reporters and security agents, cameras and cables. A disappointed New Yorker craned her neck in a futile effort to see over the mob.

"All right, I got one question," she said. "Where's Kennedy in all this?"

Sen. Edward M. Kennedy, moving along at the center of a protective Secret Service circle, was, in fact, already in the door and on the way to his headquarters suite on the hotel's 16th floor. But in a sense, the woman's question captured the confusion of Kennedy's busy day here.

"I don't think anybody knows what's going on in Kennedy's mind," said Rick Stearns, a senior Kennedy political adviser who probably would know if anyone did.

One could even wonder, watching the candidate race from delegates' meeting to news conference to fund-raiser, whether Kennedy himself had resolved what he wants from the convention that begins here Monday.

He still seems to cling to a diminishing hope that he can win the "open" convention rule fight Monday and go on to capture the Democratic presidential nomination. His more-militant aides can lay out a scenario in which the party splits among several possible nominees, and Kennedy, with a hard core of 1,250 delegate votes eventually picks up enough new backers to win.

But in private meetings with his campaign staff, Kennedy has acknowledged this possibility is remote. And so the question for him becomes what to do if the convention follows expectations and nominates Jimmy Carter.

The central dynamic of Kennedy's effort here is a long-range negotiation with the Carter side over how much Kennedy can ask in return for his promise to support Carter in the fall.

It is a negotiation carried on by a cryptic signal -- a new sentence in the standard speech, a new answer to one of the same old questions from reporters.

And today, with everyone examining Kennedy's every word with the anticipation of Kremlinologists, the signals were ambiguous.

Sometimes Kennedy seemed to be defiant, resisting any suggestion of a peace treaty with Carter. When the Carter camp sent an emissary to the Waldorf to report the president's concessions on some of the platform issues. Kennedy beamed like a man who had just won the nomination. "This is getting to be the kind of platform that I welcome to run on," he said, and immediately announced that he would "be glad to accept . . . additional concessions."

But if Kennedy still could not publicly concede that his bid for the nomination is failing, other comments during the day could be taken as a signal that he is coming closer to reconciliation.

On Friday, when he arrived here, Kennedy had laced into Carter in blistering terms, warning Democrats that "four more years would be four years too many" and joking that Carter would go around the country quoting Herbert Hoover's economic principles in the fall campaign.

Today, in contrast, there was no rough talk about Carter. The villain in today's Kennedy speeches was always Republican nominee Ronald Reagan and it was always the Democratic Party that would save the nation from "the Reagan threat."

But if the Carter side took solace in that, they also had to listen as Kennedy indirectly zapped the president with some kind words about the Republican nominee. "To, Mr. Reagan's credit," Kennedy said "i think that he has a strong belief in his views with regard to economic policy -- it's been a continuing belief."

Judging from reports from within the Kennedy headquarters, the same confusion surrounds the drafting of the speech Kennedy will give before the convention Tuesday night.

Some Kennedy advisers are pushing for a moderate tone, in which Kennedy would set forth his liberal economic principles but never mention the president's name.

Other Kennedy aides, who firmly believe that Carter's nomination would be a disaster for the Democrats in November, are reportedly telling Kennedy that, as the conscience of liberalism, he has a duty to set forth all his differences with the president and the administration's policies.

Kennedy spent several hours working on the speech this afternoon during a break from a campaign schedule as exhausting as any day during his long pursuit of primary votes this spring.

Tonight Kennedy attended a fund-raising gala on Broadway, where he was introduced by actress Lauren Bacall, who blistered the press and the Carter family and said of Ronald Reagan, he "was not much of an actor, either."

"We've heard a lot of talk that this convention is sewed up," Bacall said. "Of course, those saying that are the same people who told us that Ford would run with Reagan, Dewey would beat Truman, and Chrysler stock would go up. The only thing that ought to be sewed up is brother Billy's lip."

Kennedy then came on stage and said. "I wish Betty [bacall] would stop being so mealy-mouthed and just say what's on her mind."