A president sends 400,000 troops to a foreign land. Is he preparing for war? Just bluffing? Trying to have it both ways? Can a worried public sort it all out and engage in a constructive debate?

Scholars of the presidency say they cannot think of another moment in U.S. history when domestic public opinion was confronted with such a confusing war-peace tableau or confounding set of cross-pressures than it is now with the crisis in the Persian Gulf.

In the days since President Bush announced the deployment of an additional 200,000 troops to the gulf, public and congressional anxiety over the prospect of an unprovoked U.S. attack on Iraqi forces has risen sharply. According to academic experts and others, the ventilation of these anxieties may be making the bluff, if that is what it is, less convincing -- and war, therefore, more likely.

"What we're dealing with is a basic limitation on the capacity of leaders in a democracy to play a game of chicken," said Fred Greenstein, a professor of politics at Princeton University. "But then, nobody ever said democracy was an easy form of government."

The closest historical analogy to the brinkmanship in the gulf, Greenstein noted, is the 1962 Cuban missile crisis, in which President John F. Kennedy imposed a naval blockade on Cuba to force the Soviet Union to remove nuclear weapons from the island. That confrontation came to a head within a matter of days, however, and domestic public opinion never moved beyond the familiar rally-round-the-president phase.

The gulf showdown, by contrast, is now in its 15th week and has unfolded as a "slow-motion Cuban missile crisis," Greenstein said, in which public support has eroded -- slowly, steadily and predictably. A Washington Post/ABC News poll taken last week found that 59 percent of Americans support Bush's policy in the gulf, down from 78 percent in September.

The question now before the public and its elected representatives is how productive is it to voice these second thoughts, and in what forum?

"The danger of starting a debate at this point is that a good piece of the strategy is to convince Saddam Hussein that he has no option except to leave Kuwait," one senior administration official said. "The debate tends to work against a peaceful resolution."

"It sure would be helpful if congressional leaders would show a little consistency and perseverance and not just whirl like a weather vane every time a puff comes from the local citizenry," said Sen. John H. Chafee (R-R.I.), echoing the administration's private view that a protracted policy debate would send the wrong message to the enemy.

Such comments appear to reflect a wistfulness for an era when foreign policy was judged to be too complex to be exposed to the whims of public opinion. Historians say such an attitude of public deference hasn't survived television -- or Vietnam.

"Television has changed everything," said Henry Graff, a historian at Columbia University. "We see the soldiers in the desert, saying their 'Hi Moms.' We see their wives and mothers back home worrying. We see Saddam Hussein on television negotiating with anchormen. And pretty soon everyone feels as if he is secretary of state or commander-in-chief.

"When I was a child and we would discuss international affairs at the dinner table, my father used to say, 'They know.' Nowadays, I don't think anybody believes that. Television has robbed government of mystery. I am not talking about secrecy. I am talking about mystery. Mystery has been essential to leadership from time immemorial."

Greenstein said: "I've had this fantasy watching the debate on television this past week that some administration official would stop the camera for a second, put a hand to the side of his mouth and say, 'Look, we're just faking it. It's just a bluff. Go along with us.' But nobody can be sure it's just a bluff. We have Vietnam in our collective memory. We know that one thing can lead to another."

Most scholars of the presidency interviewed said that Bush would be strengthened by engaging in a public dialogue with Congress, despite the inconveniences that would incur.

"Public opinion has to be led, and by conducting an open dialogue with members of Congress and through the media, the president greatly improves his chances of having support for whatever steps he ultimately takes," said Nelson Polsby, political science professor at the University of California at Berkeley. "The risk in this is that you have to depend on the enemy to be smart enough to dope out our system -- and not to misconstrue open dialogue as dissent. But that risk is vastly outweighed by the need to maintain the legitmacy of the policy."

"I would dare say that the president could go up to Congress, talk about the contingencies he faces and get some sort of resolution of support," said Richard E. Neustadt, emeritus professor of government at Harvard University. "He might have to give up some flexibility, but he may come to regret not having some congressional expression of support."

Neustadt said such a formal resolution is preferable to letting the debate become "externalized away from Congress" -- conducted as it is now in a public opinion bazaar than runs from scientific polls to op-ed pages to radio talks shows to television punditry.

Others say the current loosely structured national dialogue is adequate. "I'm not sure that, for intellectual quality, we will do any better in the halls of Congress than in op-ed pages or on public affairs talk shows," said Stephen Hess of the Brookings Institution.

Hess and others noted that public opinion is more likely to be molded by leaders than it is to bubble up spontaneously from the grass-roots. "Right now, public opinion has an on-the-one-hand, on-the-other-hand quality," said Gary R. Orren, professor of public policy at Harvard. "People are at a hinge point. They're puzzled and therefore they are malleable. If someone with real credibility like a {Sen.} Sam Nunn {D-Ga.} were to rally opposition, that could have a big impact."

Many commentators fault Congress for not taking a more aggressive role in forcing a debate into its chambers. "One of the real stories here is Congress abdicating its responsibility for decisions that could lead to war," said Will Marshall, president of the Progressive Policy Institute, a centrist, Democratic think tank. "There has been a willingness to let Bush take all of the risks. Nobody wants to be accused of weakening his hand, but nobody wants to be hung out to dry if Americans start coming home in body bags. So there is a lot of ducking going on in Congress."

Marshall and others noted that there was virtually no debate over the Persian Gulf policy in this fall's congressional campaigns.

"I think the public really missed the boat on that one -- they lost their big chance to affect public policy," said historian James MacGregor Burns. "My sense is that the public is immobilized, almost mesmerized, by the crisis. I think it has something to do with their sense of distance from Washington. It is almost as if they are saying, 'Okay, George, you're sticking your neck out. It's your job, not ours.' " He added his belief that "the first real casualties will produce a big revulsion in this country."

One White House official said there was little debate in the election campaigns because there was "virtual unanimity of support" for the policy. He acknowledged that such unanimity began to fray two days after the election -- when Bush announced the additional troop deployment and made more explicit the option of an offensive strike. But he dismissed as pure "bunk" the oft-voiced critique that support has eroded because Bush has not laid out a clear rationale for the deployment. "People want to know why you are there in one sentence," he said in frustration.

In fact, the administration has offered several rationales -- none of them inconsistent with one another, but the combination appears to have created public confusion.

"Bush has made speeches in which he lays out reasons A, B and C for doing what he's done," said Hess. "And a lot of commentators are saying, 'Why doesn't he give us a clear rationale.' But he has given the rationale. People who complain he hasn't probably just don't like the policy. For them, this isn't a problem {speech writer} Peggy Noonan can be called in to fix. It's bigger than that."

Staff writers Dan Balz and John E. Yang contributed to this report.