When the Des Moines Register released a poll a week ago showing Vice President Gore leading Bill Bradley by 21 percentage points, the reaction in the two campaigns was curious and unexpected. Bradley staffers beamed. Gore aides wore long faces.

The Register poll showed Bradley making no headway against Gore despite a heavy television advertising buy and considerable personal campaigning in the state. So why the upbeat reaction? "In terms of expectation, it was quite helpful," said Gina Glantz, Bradley's campaign manager.

Nine days before Iowa opens the nominating process in Campaign 2000, Gore and Texas Gov. George W. Bush appear certain to receive the most votes in the state's precinct caucuses, as the superior resources of the two party front-runners have begun to affect the direction of the nomination battles.

But Gore and Bush are doing everything they can to ensure not only that they win the most votes here on Jan. 24, but also that they are judged the winners. Their rivals are doing everything they can to spin likely losses into gold as the competition moves to New Hampshire the following week. As a senior Gore adviser put it: "We're battling an expectations game in Iowa."

The game of expectations represents a subtle but significant part of the warfare among the campaigns in the final days of January. It may prove as important to Bradley, John McCain and Steve Forbes as it is to the two front-runners.

The Gore and Bush campaigns believe that consecutive victories in Iowa and New Hampshire--something no candidate in an open nomination fight has done since Jimmy Carter in 1976--could cripple the insurgent candidacies of Bradley and McCain. Which is why, in New Hampshire, Bradley and McCain are playing their own expectations game by tamping down assertions that they must win there to stay alive.

Asked a few days ago what would happen if he did not defeat Bush in the New Hampshire primary, McCain offered this tortured answer: "I think we're in grave difficulty," he told a cluster of reporters. "But obviously as we all know, the definition of 'win' is in the view of those who judge who winners and losers are. But yes, we have to 'win' in the view of those who judge these things."

The smiles on the faces of the Bradley supporters who appeared the morning the Des Moines Register poll was released began to fade by the time the Register-sponsored Democratic debate concluded later that day. During the hour-long forum, Gore repeatedly put Bradley on the defensive, setting the tone for perhaps the most difficult week the former New Jersey senator has faced in months.

Gore hammered Bradley on agriculture policy, brought a New Jersey farm family to Iowa to complain that Bradley had no interest in the subject and threw an ad on the air in Iowa featuring the state's Democratic senator, Tom Harkin, attacking Bradley's record on farm issues. He aired a radio ad in New Hampshire featuring Massachusetts Sen. Edward M. Kennedy, who claimed that Gore has the best plan to move the country toward universal health care--a direct shot at the centerpiece of Bradley's "big ideas" agenda. Adding to Bradley's woes, the vice president on Sunday will get the endorsement of the Boston Globe in the New Hampshire Democratic primary.

Bradley responded to Gore's attacks in uncharacteristic fashion for a candidate who has promised to stay above the fray and resist what he calls the "rat-a-tat" of negative campaigning. He attacked Gore's mixed record on tobacco (the vice president was a strong supporter of tobacco subsidies as a senator from Tennessee) and accused Gore of injecting racism into the 1988 presidential campaign by raising the issue of Willie Horton and prison furloughs against Michael S. Dukakis in the Democratic primary.

Bradley and his advisers also struggled to dampen expectations in Iowa after raising them with an $800,000 January television buy and a commitment to spend most of the month campaigning in the state. Concerned that a weak showing in Iowa could damage his stronger campaign in New Hampshire, Bradley looked for ways to campaign in both places at once. He even rented a satellite truck to follow him in Iowa to beam him back to New Hampshire in coming days.

Glantz set the bar of expectations dramatically low, saying Bradley only needed to match what Kennedy got against Carter (then a sitting president) in 1980, which was 31 percent. Gore adviser Robert Shrum, a longtime Kennedy aide, scoffed at that: "I think Senator Kennedy would say that's not a precedent anyone who wants to win the nomination would cite."

Glantz insisted that Gore needs 60 percent or better in the caucuses to claim victory. "We have always said that going to Iowa is tough. . . . It's clear he's got all that institutional support and the labor guys are sending people in. . . . It provides a challenge."

Gore advisers claim they too are worried about Iowa. They say that the race with Bradley may be closer than the public polls suggest and that the nature of caucuses, where the key is finding supporters willing to devote several hours of their evening to vote, is less predictable than primaries. Many remember that in 1984, Walter F. Mondale won the Democratic caucuses with 49 percent of the vote, but Gary Hart, with a surprising 16.5 percent, grabbed the headlines--and later the New Hampshire primary.

"I do think Bradley has hit a wall in Iowa," a Gore adviser said. "But he could very easily, depending on how you decide to set the bar, exceed expectations." When asked what support Gore will need in Iowa to give him momentum heading into New Hampshire, the Gore adviser balked. "I'm not that stupid," he replied. "It will evolve over the next few days."

Bradley's week on the defensive followed by several days a similarly difficult stretch for McCain, who was thrown off stride by questions about his intervention before the Federal Communications Commission in behalf of a campaign contributor. "What it did," a top McCain adviser said, "was for 4 1/2 days muddy up our message. But from everything we're seeing privately and publicly, from our crowd size to our enthusiasm, this is a campaign on the move."

The Arizona senator appeared to have regained his footing in New Hampshire this past week, continuing to draw large crowds at town hall meetings across the state and winning the Boston Globe's endorsement in the New Hampshire GOP primary. McCain also joined an increasingly pointed debate with Bush over taxes and Social Security with a risky strategy of appealing to GOP voters by promoting a small rather than a large tax cut.

Bush's advisers argued that they had the better of the argument, and Scott Reed, who managed Robert J. Dole's 1996 campaign, underscored the gamble by McCain by saying, "The secret to January is to be an economic conservative, a consistent economic conservative."

McCain sought to redefine economic conservatism within the party by arguing that the fiscally responsible (read "conservative") position is to cut taxes half as much as Bush and set aside enough of the surplus to protect Social Security and begin to pay down the debt.

The Bush campaign, wary of allowing McCain's argument to take root, responded with a television ad that sought to reassure GOP voters that the governor's big tax cut still reserved enough of the surplus to extend the solvency of Social Security.

But if the debate on the GOP side remained largely between Bush and McCain, the dynamic of the Republican campaign--and therefore the manipulation of expectations--differed from the Democrats, principally because Bush faces separate opponents in Iowa and New Hampshire.

In Iowa, McCain is not formally competing in the caucuses, although it is not clear whether he will be hurt in New Hampshire if he finishes fourth or fifth here. "I don't think it matters," Reed said. "I think he's gotten away with flying over Iowa and putting all the focus on New Hampshire and South Carolina."

Bush's main rival in Iowa is Forbes, who hopes to jump-start a campaign that has struggled throughout the fall and winter with a strong second-place finish. Forbes's goal is clear: He needs to finish closer to Bush than he did in the Iowa straw poll last August, when he trailed the governor by 10 percentage points.

Bush's campaign, like Gore's, has attempted to set a low bar, arguing that all the front-runner needs is to beat the best showing by a Republican in previous caucuses--the 37 percent Dole won in 1988. "We agree we have to have a bigger spread over Forbes than in straw poll," a Bush adviser said. "That's our goal and we're working hard." But mindful of polls showing Bush with support of about 46 percent of likely GOP caucus goers, he added, "The front-runner always underperforms his number."

Both Bush and McCain are concerned about how well Forbes does in Iowa; aides to each candidate argue that the worse Forbes does in Iowa, the better it is for them. Republican pollster Bill McInturff said about two-thirds of New Hampshire GOP primary voters are predisposed to support someone other than Bush. If Forbes does well in Iowa, McInturff said, "It complicates who is the Bush option in New Hampshire."

"The goal is to have Forbes going down," a Bush adviser said. "The hope is that he is seen as not having met expectations and basically people feel the decision they have to make in New Hampshire is between McCain and Bush. The overwhelming number [of Forbes supporters] are voting on the flat tax. Those votes will more often accrue to us."

For McCain and Bradley, the challenges are similar as Iowans prepare to vote. With New Hampshire crucial to the hopes of both, and with Bush and Gore having more resources at their disposal, they must find a way to make the results in Iowa an asset and not a liability.