Ah, the folly of youth. On Sept. 24, 2007, I pitched a story to my boss at NEWSWEEK about "Barack Obama and young voters—specifically, whether they can actually help him win the nomination or whether they'll just stay home, you know, watching MTV and eating Doritos as they have in the past." With Obama trailing Hillary Clinton by 10 points in Iowa, his campaign manager, David Plouffe, had just told reporters that youngsters were "Barack's core support—in effect, his hidden vote." I'm 25; my editor is 31. "I like this a lot," he replied. "Proceed, my friend."

A week later, after interviewing campaign staffers and independent observers, I sent him a profile of Obama's nimble Iowa youth program. Haunted by the specter of Howard Dean, whose hordes of orange-hatted out-of-state volunteers failed to fulfill the Vermonter's youthful potential in 2004, Team Obama had already hired four times as many staffers and invested five times as much money in the state, opening an unprecedented 31 offices and launching a novel "BarackStars" program to target the 40,000 untapped 17-year-olds set to turn 18 before Election Day. Rob Sand, a 25-year-old former Deaniac, admitted that he'd skipped the 2004 caucuses. But this time was different. "I'm more excited about Obama than I was about Dean," he said. "Dean was polarizing. Obama brings people together." Although counting on kids to carry the caucuses was "a tall order," I wrote, "the potential, at least, is there."

My boss liked the story—but his boss, a 43-year-old former Washington bureau chief, was skeptical. He'd heard the spiel before. Gene McCarthy. Gary Hart. Bill Bradley. Dean. "If young voters show up and Obama wins Iowa," he said, smiling as he slumped on an office sofa, "it's a big steak dinner for you guys. And I'm buying." My editor nixed "The Audacity of Youth" that night.

Exactly three months later, I arrived at the apartment of Paul Tewes, Obama's Iowa state director, as the icy streets of downtown Des Moines filled with young Obamaniacs hugging and cheering, "We did it!" Upstairs, scruffy postcollegiate staffers squeezed between couches and credenzas to celebrate the senator's surprise victory. Cans of Bud Light covered every surface. Youth turnout was up 135 percent from 2004, and the under-25 set alone gave Obama 17,000 votes, a 26-year-old speechwriter told me. Obama's margin of victory? Twenty thousand. "We did it" was right.

Rob Sand e-mailed the next morning. "This," he wrote, "is our next president."

Born in the 1980s, Sand and the supporters chugging Bud that night are what generational theorists call "millennials." (Full disclosure: I'm one, too. Further disclosure: I'm also a registered independent.) Now, a month after Iowa, my boss's boss is well aware that millions of my peers have fallen under the spell of the freshman senator from Illinois. At this point, the statistics seem almost stale: with youth turnout doubling, tripling and even quadrupling in the 30 contests to date, Obama won the 18-to-29 demographic by 4-1 in Iowa, 3-1 in New Hampshire, 3-1 in South Carolina and 2-1 in Nevada, and he trounced Clinton, often by as much as 50 percent among young voters, in 10 of the 13 Super Tuesday states with available data. (On Saturday, Obama swept the primaries and caucuses in Washington, Nebraska, Louisiana and the Virgin Islands.)

But while the figures make for catchy headlines, they don't tell the whole story. What's clear to me after three months of chasing the candidates from coast to coast for my Newsweek.com blog, Stumper, is that it's not so much the strength of Obama's youth support that's significant—it's how fully and seamlessly he embodies the attitudes, aspirations and shortcomings of the generation that's rallied around him. After all, not every Obamaniac is under 30 (sources say that some are even—gasp!—middle-aged). And Clinton tends to best her hipper rival among young voters in states like California and Massachusetts whose populations are too large and diverse for Obama to overwhelm with ground troops and captivating speeches (the Hispanic vote, which favors Clinton, may also contribute). In truth, to call the Democratic primary contest a battle between young and old would be reductive. Instead, Democrats are struggling to choose between different generational views of governance. On one side is Clinton, the consummate baby boomer. On the other is Obama—not a late boomer, as his birth date would suggest, but the first millennial to run for president. For better and for worse.

Summing up an entire generation with a few broad brush strokes is always hazardous, especially in politics. But as a millennial, some of the stereotypes ring true. According to Morley Winograd and Michael D. Hais, authors of "Millennial Makeover: MySpace, YouTube, and the Future of American Politics," millennials "aren't confrontational or combative, the way Boomers (whose generational mantra was 'Don't trust anyone over 30') have been." Instead, millennials belong to what social scientist William Strauss calls a "civic generation," drawn to issues of "community, politics and deeds, whereas the boomers focused on issues of self, culture and morals." Reacting against the excesses of our parents—especially their efforts to advance moral causes through partisan politics—we prefer to address problems by reforming institutions from within. We're team players, say Winograd and Hais, conditioned through constant social interaction (often online) to "find consensus, 'win-win' solutions to any problem." We distrust traditional channels of information and prefer to learn from peers (again, often online). We are diverse. After George W. Bush, we believe, as Obama youth-vote director Hans Riemer puts it, "that it matters who's running the government—and that government is a powerful way to make this country a better place." And we're more optimistic than boomers about the possibility of change. According to a January survey by Frank N. Magid Associates, a plurality of boomers (43 percent) believe that the 2008 election will leave the United States unchanged or worse for wear. Only 32 percent of millennials agree—and a full 40 percent say that it will make America stronger.

Obama's message first struck me as essentially millennial three days after the Iowa victory party, on an unseasonably balmy Sunday in Manchester, N.H. When I arrived at 9 a.m. for a rally at the historic Palace Theatre, I found a line of anxious supporters stretching around the block. Hundreds never got seats. At the time, Obama led by at least 10 points in the New Hampshire polls, and when he swept onstage, the combination of rapturous applause and U2's "City of Blinding Lights" made the moment seem cinematically inspiring. It appeared obvious—at least to someone covering his first presidential election—that the Illinois senator was destined to repeat his Iowa rout. First, Obama thanked Kimberley, the young volunteer (and daughter of a Congolese immigrant) who introduced him. "Hope is an idea, it's a feeling, a belief, a revolution, a role, a possibility," she'd said. Then he gave a shout-out to regional field director Jack Shapiro, one of "the young people who are pouring their hearts and souls into this campaign." Finally, Obama gave a speech brimming with pure millennial uplift. "It's time for us to put aside the partisan food-fighting," he said. "If you know what you stand for, if you know what you believe in, if you know who you're fighting for, then you can afford to reach out to those who don't agree with you on everything. We can create the kind of working majority that we haven't seen in this country for a long, long time. If I've got the American people behind me, I fear no man. Nobody can stop us. We can do everything that we want to get done."

It was all there. The optimism. The diversity. The sense of community. The faith in government. The repudiation of partisanship and the call for consensus. Obama had delivered a plea for practicality, not a blazing boomer war cry. But the crowd, now on its feet, was thrilled nonetheless. "I wouldn't vote for Hillary," Charles Silva, 72, told me afterward (Obama's millennialism is not just for millennials). "Correctly or incorrectly, she has a lot of baggage with her. I think she represents looking back. And Obama represents looking forward." Even I was wobbly. "It's going to sound horribly uncynical," I wrote on Stumper a few minutes later, "but there's really no other way to say this: Obama's on fire."

That evening, I drove 45 minutes to the coastal town of Hampton for a Hillary event. The effect was hardly as electric. Ninety minutes after the scheduled start of her speech, Clinton had not yet arrived—and the audience in the Winnacunnet High School cafeteria was getting antsy. The preshow soundtrack had cycled through Sheryl Crow's "A Change Would Do You Good" (hint, hint) at least four times, and the staffer hurling HILLARY T shirts and quiz questions at the increasingly listless blue-collar crowd wasn't exactly connecting. By the time Clinton finally appeared, the cafeteria had partially emptied out. Unfazed, she delivered a punchy, pointed, 15-minute opening statement—"There's a difference between talk and action, rhetoric and reality"—that framed Obama as an ordinary politician with an extraordinary teleprompter. "She's fighting to stay in the game," I scribbled in my notebook. Obama is fond of saying that Clinton embodies the character and conflict of the baby boomers. "The battles between [Newt] Gingrich and [Bill] Clinton were battles that took place in dorm rooms ... 30 years ago," he said in December. "We're re-litigating sex, drugs, rock and roll, Vietnam." The premise of Hillary Clinton's presidency is that the combat will continue, and its promise is that only she knows Washington well enough to win. As adviser Sidney Blumenthal recently told The New Yorker, "it's not a question of transcending partisanship. It's a question of fulfilling it."

As I sat in the Winnacunnet cafeteria, I couldn't help but hear in Clinton's remarks an echo of that combative "us versus them" mind-set—instinctive, almost, after 20 years spent defending her most precious political values from assault by her peers. "You've got to have an understanding of how you bring about change that is rooted in reality," she said, listing the precise numbers of New Hampshire children her work had helped insure and vaccinate. "Wishing doesn't make it so." When Clinton, normally inaccessible, opened the floor for questions—34 in all, or two hours' worth—the reporters in the press pen cracked jokes about her desperation. My Stumper dispatch was no kinder. "If you ignored the Secret Service agents, the hordes of reporters and the fact that the candidate was wearing a dark pantsuit and a bright pink blouse, last night's Democratic campaign stop looked a lot like a Joe Biden event," I wrote. "The crowd was not young. The room was not full. And the guest of honor, Hillary Clinton, spoke for two straight hours." Joe Biden? Ouch.

Two days later, Clinton won the New Hampshire primary. Humiliated, the pundits and prognosticators who expected an Obama victory went into paroxysms of guilt. We trusted the polls! they said. It was the echo chamber! But no one mentioned generational bias. Most of the reporters in the Winnacunnet press pen were embeds or bloggers—the eyes and ears of their newsrooms. Almost all were my age. And for many, Iowa was their first big election. Seduced by the familiarity—the "rightness"—of Obama's message, it was hard, as millennials ourselves, not to assume that it appealed equally to everyone. But the truth is, we're far more coddled and comfortable than previous generations. Weaned on self-esteem and offered unlimited choice (technology again), we grew up with a sense of entitlement—specifically, for control. And in New Hampshire, it seems, some Democrats heard something like entitlement in Obama's gauzy pledge to "change Washington." Untroubled by debt, or joblessness, or unsupportable children, Obama's millennial fan base (and the older, typically wealthy whites who vote with them) can afford the luxury of privileging process over policy. Clinton, on the other hand, ditches the packaging and goes straight to the product—the plans she'll fight Republicans to pass. It may not have the same "cool factor" as Obama's brand, but to Clinton's base of women, Latinos and downscale Dems, it's enough to seal the deal.

Now that the race is deadlocked, I have no idea which generation of leadership Democrats will choose: the boomer Clinton, who promises to play by the old rules and win, or the millennial Obama, who promises to change the rules entirely. But the next time I'm tempted to write that Obama's "on fire," I'll remember Joanne Barton, a New Hampshirite I met at Exeter's Loaf & Ladle café that Sunday between the Obama and Clinton events. Decades ago, Barton suffered a car crash while pregnant; her baby was born with disabilities, and after more than a dozen operations, she still walks with a cane. Clinton had always been a hero. "When I was in that hospital bed, I saw her on TV with her chin up, leading Chelsea by the hand," she told me. "That was after Monica, and it's always inspired me to keep my chin up, too." Barton was still deciding between the candidates when we met, but two days later she went with Clinton. "I'm not a rah-rah person," she said. "And Obama's relying too much on rah-rah. He's not addressing our concerns."

Whether true or not, there are plenty of Democrats who agree. So I'm going to hold off on that steak dinner for now.