CONCORD, N.H. -- The traffic-clogging lines that curl into Barack Obama's rallies contain a diverse group, from mothers toting young children to bearded professionals in sturdy all-weather boots. But perhaps most desirable are voters like Lynn Xie, who waited in a quarter-mile-long line last week to hear the Illinois senator speak.
"It's really exciting for me," said the Dartmouth College student, boning up for her first presidential election. "I just turned 19."
Obama turned the Democratic contest on its ear last week with a decisive victory in the Iowa caucuses, generated in large part by overwhelming support from voters younger than 30.
Nearly six in 10 in that age bracket supported Obama - more than five times the number that voted for Sen. Hillary Rodham Clinton of New York.
There were as many Democratic Iowa voters in their teens and 20s as over age 65, resulting in a 30 percent increase in young caucus- goers compared with 2004.
The Obama campaign is trying to replicate that result in tomorrow's New Hampshire primary, and perhaps ride it to the Democratic nomination.
The target is enticing: 86,000 New Hampshire residents reached voting age over the past five years, according to a recent report by the Carsey Institute at the University of New Hampshire. That, combined with 207,000 people moving into the state, many of them young families, "has produced considerable turnover in the pool of potential voters," the report found.
It is a strategy not without risk. Conventional wisdom holds that older people are more regular voters, and campaigns have long found it more productive to target those who have reliably gone to the polls in the past than to rely on the unknown.
Even so, young voters have long been a Holy Grail for politcos. In recent years, efforts like MTV's Rock the Vote and Sean "P. Diddy" Combs' "Vote or Die" have tried to mobilize young voters - with mixed results.
"Let's get real: Howard Dean had that too, and it only took him so far," said Jason Palitsch, 18, a student at Northeastern University in Massachusetts attending a Clinton rally this week. But in an era when social networking Web sites are sponsoring presidential debates, the rules may be undergoing a rewrite.
Clinton has responded. She is trying to reach out to young voters in New Hampshire, inviting a few for a ride on her campaign bus on Saturday to talk with her and her 27-year-old daughter, Chelsea.
"I want to hear from young voters about their concerns and encourage them to participate in this incredible process," Clinton said in a statement.
The Obama campaign has organizations on 600 college campuses, and its student arm was launched on the Facebook Web site, said spokeswoman Jen Psaki.
"We knew we didn't want students just to be props or people waving signs at rallies," she said.
As campaigns seek support from young voters, they must address a variety of issues, not a single theme, interviews show.
"There has been focus on Iraq in terms of the media, but the environment and energy, to our generation, that's the big problem we see," said Gray Chynoweth, 29, a technology lawyer and former head of New Hampshire Young Democrats. "Our generation sees global environmental damage that has happened over the past decades that is going to be our challenge to fix."
For Allison Goldsberry, 26, a freelance Web designer from Massachusetts, "health care is definitely a big one, and the economy. Those are the two big things for young people."
An undecided voter, Goldsberry attended Democratic and Republican campaign events last week with her friend, Alexander Svirsky, 33, an engineer.
"I've been laid off, he's been laid off," she said. "We know what it's like to lose your health insurance and your job, and then kind of have to pick up the pieces and put them back together again."
Goldsberry said she's not sure that young voters will be pivotal in the election.
"A lot of young people are moving around. They go to school maybe in a different state, maybe move someplace else, so I don't think they keep up to date with being registered," she said.
Still, Obama drew thousands of young people to campaign appearances last week, sending many to overflow rooms when the gymnasiums and theaters grew too crowded. His message of bridging partisan divides and refusing to fight old battles seems to be resonating. At 46, he is the youngest contender of either party, and his mixed-race heritage and fast rise from a Chicago community organizer to the U.S. Senate offering a compelling narrative.
Tarah Guttman, 27, a physical therapy student from Nashua, likes Obama's pledge to increase teacher pay.
Guttman is leaning toward voting for Clinton, but harbors doubts about siding with the wife of a two-term president, following two terms of the son of another president. "You feel like maybe it's being controlled by two main families," Guttman said.
Jesse Heath, 20, a student at New Hampshire Technical Institute in Concord, said he is backing Obama because "he's not been corrupted by lobbyists."
"I think the corporate hold on Washington is the root of most of our problems today, from global warming to the war in Iraq," Heath said.
The quest for young voters comes as the 2008 election increasingly centers on the issue of change. On the Democratic side, a youthful-looking John Edwards insists he has the convictions to bring change to Washington.
Among Republicans, former Massachusetts Gov. Mitt Romney is arguing that he is the best candidate to instill change, given his record as a corporate turn-around artist and savior of the Winter Olympics in Salt Lake City.
Romney came in second in Iowa, where 11 percent of Republican caucus-goers were younger than 30, and nearly three in four were age 45 and older.
Republicans and Democrats face a tough job trying to sway today's young people, who may be the most sophisticated consumers ever.
"We are a generation that has been marketed to more than any generation," said Chynoweth, the former Young Democrats head.
Young people can be swayed by a "coolness factor," acknowledged Chynoweth, who said he resigned from the Democratic group to endorse Clinton. "I think competence is cool," he said.
Clinton has been making the same point here, and tomorrow's vote will reveal which of the competing campaign messages is most persuasive among young voters.