Washington, D.C. - Experts say young voter turnout likely will build on the surge from recent presidential elections as more campaign efforts target that age bracket, but some say it's too soon to tell if the trend will hold through the November election.

"People are sort of like, 'Oh, they are voters,' as opposed to 'Will they be voters?'" said Karlo Marcelo, a research associate with the University of Maryland's Center for Information and Research on Civic Learning and Engagement, or CIRCLE.

Young adults have turned out at the highest rates since 2000 in primaries and caucuses in Iowa, New Hampshire and Florida, according to the center's analysis of voter turnout and preferences based on entrance and exit polls.

The youth turnout rate for the Iowa caucuses rose to 13 percent from 4 percent in 2004 and 3 percent in 2000. Young adults supported the winners for both parties by the largest margins of any age group.

Days later in New Hampshire, youth turnout was 43 percent, compared to 18 percent in 2004 and 28 percent in 2000.

Those rates are probably record-breaking, but the polls and statistics from decades ago don't exist to help evaluate such a claim, said Marcelo, who expects the higher rates to continue among young adults in November.

"They could be the trump card, but we'll see," he said.

Leaders of national Democratic and Republican college groups said Tuesday that young adults are looking for candidates who acknowledge their concerns for the issues.

Even before the turnout rates surged, young adults played an important role in campaigns and public debate, and that's becoming more apparent, said Ethan Eilon, executive director of the College Republican National Committee.

His counterpart at College Democrats of America, LaToia Jones, said young voters must remind candidates that their parents aren't the only ones with the power of the vote.

To win in November, candidates will need to reach out to young people and heed that message, said Kat Barr, deputy political director of the nonpartisan, youth-centric Rock the Vote campaign.

Barr dubbed 2008 "the year of the youth vote" and said voters under 30 - who, studies show, have less party allegiance than older voters - are proving to be a crucial component of political victory for candidates.

Illinois Sen. Barack Obama, perceived as the favorite among young voters, captured more than half the youth vote in every major Democratic contest leading up to Florida's formally uncontested primary on Tuesday, according to CIRCLE.

In Florida, Sen. Hillary Clinton of New York garnered 44 percent of the Democratic youth vote, barely nudging past Obama's 43 percent. John Edwards, who withdrew from the race Wednesday, received 11 percent.

For the Republicans, young adults have favored different candidates from state to state. Sen. John McCain of Arizona got 30 percent of the votes cast by young GOP voters in Florida on his way to a win there Tuesday. Rudy Giuliani, who also ended his presidential bid Wednesday, took 19 percent of the under-30 vote.

The total youth turnout rate in Florida hit 13 percent, more than tripling the 2000 rate.

The turnout of eligible young adults has averaged less than one in five in the contests so far, ranging from 5 percent in Nevada to the striking 43 percent in New Hampshire, where overall turnout was more than half the eligible population, according to CIRCLE.

"The more attention that is paid to young people, the more likely it is they'll vote," said Adam Fogel, the right to vote director of FairVote, which promotes voting access and election reform.

Candidates and get-out-the-vote organizers recognize that point, he said, and their efforts are contributing to increasing registration and participation among voters under 30. Campaigns' youth outreach directors tap a younger audience and cater events to college crowds.

It's far easier for campaigns to target college students than those who aren't in college, Marcelo said, because they are on campuses.

Voting advocacy groups like Rock the Vote and HeadCount appeal to young adults using music and pop culture, and social networking Web sites allow students to show support for specific candidates and issues.

That's great for raising awareness, Fogel said, but the biggest hurdle to getting young adults to vote is registration and education about voting.

In 2004, people under 30 registered to vote at the highest rate in three decades, and about 80 percent of those registered - or about half of all eligible young voters - cast ballots.

"There are too many people who basically just weren't taught how to vote," from registering to requesting absentee ballots or voting from overseas, Fogel said.

Access to that how-to information is increasing, especially as it spreads online - the home turf of a Web-savvy generation of young voters. Some states are also pursuing ways for voters to register online.

And for U.S. citizens working, studying or serving in the military overseas, the nonprofit Overseas Vote Foundation launched a Web site in October to help them find and print state-specific registration and voting forms, deadlines and follow-up information.

Whether those outreach and informational efforts will result in an Election Day turnout by young adults that surpasses the 2004 surge is uncertain, said Curtis Gans, co-founder and director of the nonpartisan Committee for the Study of the American Electorate.

"My guess is that young people will turn out at higher rates than any year since 1992, with the exception of 2004," when college-age voters in battleground states demonstrated hefty opposition to the incumbent president, Gans said. "I don't know whether the same fervor will exist when we get to the general election and George Bush isn't running."