The Iowa caucuses have often been the scene of pitched battles, big surprises and vigorous debates. But on the eve of the opening event of Campaign 2000, there is little anticipation and even less passion here about the presidential nomination fights that will begin to unfold on Monday night.

With two days of campaigning left in Iowa, the candidates crisscrossed the state today in an effort to build excitement and swell turnout for the caucuses. In the final hours, the crowds have grown more boisterous. But as often as not this week the voters have acted more as polite spectators than enthusiastic participants in the process.

"Usually by this time you've got a lot of people talking about the different candidates," said Alan Clark, the Republican county chairman from Grinnell, Iowa. "I'm just not hearing it. It's just not coming up."

Part of the voters' indifference stems from the lack of suspense about the outcome on Monday night. Texas Gov. George W. Bush is expected to defeat his five Republican rivals in the caucuses, while Vice President Gore has strengthened his commanding lead here over a now-defensive Bill Bradley, who will be forced to rethink his New Hampshire strategy if he suffers a big loss here Monday.

A poll published in Sunday's editions of the Des Moines Register shows that Bradley has slipped in the past two weeks, with Gore now leading 56 percent to 28 percent. Among Republicans, Bush stands at 43 percent, with magazine publisher Steve Forbes second at 20 percent. No other Republican is in double digits.

One question left unanswered here is how Monday's results will shape the final week of campaigning in New Hampshire, where both races are more competitive and where Bush's stiffest competition comes from Arizona Sen. John McCain, who is not competing in Iowa.

But party activists and political analysts point to other reasons why the nomination fights this year--both here and in subsequent states--may lack the drama and significance of past battles.

Those elements begin with the economic good times that have fueled a sense of national optimism while muting demands for dramatic action on policy. But the reasons also include the absence of sharp ideological divisions within the parties, a dramatic policy dispute or the energy provided by the kinds of charismatic or movement-driven candidates seen in past races.

"This is not a year where there's a particular dynamic in either party," said Republican pollster Bob Teeter. "There's nothing going on."

The candidates and their advisers, who now are engaged in daily combat to affect voter attitudes and influence media coverage of the races, would disagree sharply with Teeter's assessment. From their bunkers, the campaign of 2000 has never been more intense. "For me it's pretty exciting," said Bush media adviser Mark McKinnon. "It feels to me like it's really kicked in."

Along the trail this week, Bush has come under fire from his principal opponent here, Forbes, who has challenged Bush's antiabortion commitment on an almost daily basis. McCain attacked the governor for attacking him on taxes. In the Democratic race, Gore and Bradley sparred over racial profiling, agricultural policy, health care and leadership styles.

But these skirmishes likely have registered more with the competing campaigns and the media than with the public. The differences among the candidates often seem like small distinctions to many voters, who see a field of Republicans all promising to cut taxes and opposing abortion and two Democrats who say they want to expand health care and invest in education while differing over the details.

Nor have the candidates done much in their personal campaigning to help engage the interest of the voters, with many still delivering months-old stump speeches largely devoid of edge or emotion. Candidates such as Alan Keyes or Gary Bauer appear to have committed and enthusiastic supporters, but Bush said publicly this week his biggest concern is complacency among his supporters--and his campaigning here has done little to stoke a sense of urgency about Monday's vote.

Organizers say privately that it has been particularly difficult to generate enthusiasm among potential caucus-goers this year because the candidates lack flair or personal charisma. As Phil Roeder, a former Iowa Democratic Party official, put it, the contest between Bradley and Gore sometimes has had all the excitement of "the valedictorian and the salutatorian running for class president."

But if there is no passion for the leading candidates, neither is there any great dislike for them, which has also affected the attitudes of party activists. They have no one they are passionate to vote against.

Jerry Crawford, an Iowa Democrat supporting Gore, recalled the last two-person Democratic contest in Iowa, the bitter, 1980 race between President Jimmy Carter and Massachusetts Sen. Edward M. Kennedy. "It was hard to find anyone who didn't dislike one of the two candidates intensely," Crawford said. "In this race, most people like both candidates in some measure. That's a completely different dynamic. It's not one that creates the same zeal."

The same appears true on the Republican side, where Bush and McCain, the top two candidates nationally, have earned the respect and admiration of most GOP voters, regardless of whom they are supporting for the nomination. Even the other Republican candidates have generated good reviews for the debate performances from party activists.

More fundamentally, the campaigns in both parties lack a great debate or a truly dividing issue. The fight over taxes and Social Security may yet develop in the Republican race in New Hampshire, but the health care debate between Gore and Bradley has not risen to capture the imagination of the voters. Perhaps it has done the opposite.

"Had the Democratic debate around health care become a real debate about the role of government, you might have drawn voters into the discourse and increased interest," said Democratic pollster Stan Greenberg. "But the debate was more about the numbers, which is pretty arcane for most voters. It's not the stuff of high politics or high turnout."

Teeter said the campaigns reflect the country. "The country has pulled back somewhat," he said. "You can look back and say the country went a little left in the 1960s and '70s and a little right in the '80s. It's pretty happy and satisfied and pretty middle right now."

Democratic pollster Peter Hart said that most voters see Bush, McCain, Gore and Bradley as nonideological and nonthreatening, as "four centrists that don't make people feel uncomfortable."

"You'll have Republicans who dislike Gore intensely and Democrats who dislike Bush intensely, but for most of the nation, you're looking at the middle of the spectrum," Hart added. "It's the first time I can think of where the four major contenders are not either on the left or the right."

That is a sharp contrast from past nomination battles. The conservative wing of the Republican Party fueled Ronald Reagan's rise to power. In 1992 and 1996, the GOP race was shaped by a conservative challenge to the party establishment by commentator Patrick J. Buchanan. In 1984 and 1988, the Democratic races drew some of their energy from the left-of-center candidacy of Jesse L. Jackson.

The absence of an energized left or right this year makes insurgent candidacies more difficult. Bradley has sought to run to Gore's left, but the vice president has nailed down constituencies on the left such as organized labor and environmentalists. In the Republican race, no conservative candidate has managed to coalesce the right against Bush.

Neither nomination fight this year appears to have developed into a battle to redefine the party, as Gary Hart's "new ideas" candidacy in 1984 and Bill Clinton's "New Democrat" campaign in 1992 did. Bush has shown signs of running that kind of campaign with his talk of "compassionate conservatism," but has been more cautious in challenging his party's conservative constituencies.

Greenberg said he also has been surprised that Bush's candidacy has not done more to energize a Republican Party yearning to recapture the White House and inflict revenge on President Clinton.

"Part of it may be the purposeful dousing of the ideological fires by Bush," Greenberg said. "He's come forward to claim the presidency for the Republicans, but he's not come forward to claim it for the right. He's avoided all the symbols and rhetoric to get the right excited. And there is a sense of the right being tactical, of 'Let's be sure we win this time.' That may have its price."

Here in Iowa, one other element of the campaign appears to have dampened enthusiasm and that is the sheer length of it. For many voters, there was barely a respite after the 1996 campaign. "We had about a year off and then it started," Alan Clark said. "Then there was all the stuff coming out of Washington. People are just kind of burned out."

Some party officials say they have begun to see more interest by voters in the final days of campaigning, but Jim Dvorsky, the GOP chairman in Linn County, said that "the energy level" began to sag when candidates like Elizabeth Dole dropped out. "At first I was hoping to have a 20 percent increase in turnout and that's what we budgeted room space for," he added. "But I think we'll fall short of that. With Gore and Bush anointed as front-runners, that does have a damaging effect on turnout."