COLUMBUS, Ohio -- Sean "Diddy" Combs danced in front of his young hip-hop fans just hours before the election, reminding them one more time to vote for Barack Obama.

"Stay in them lines," he shouted above the cheering.

A day later, a small plane circled over The Ohio State University for hours, towing a banner: "Vote Obama Today."

Obama's campaign did everything it could to make sure young people got the message.

It worked, but maybe not as well as they had hoped.

Young voters went more heavily Democratic than in any election since at least 1992. Associated Press exit polls showed that voters under 30 in Ohio backed Obama by a 2-1 margin.

"Obama got young people excited," said Tricia Heschel, president of the University of Dayton College Democrats.

The group worked closely with the Obama campaign on get-out-the-vote efforts, making sure students knew where to vote and what they needed when they got there, she said.

Obama also was able to convince younger voters that they could make a difference, said Bruce Newman, a DePaul University professor who specializes in political marketing.

"That's a target market he was able to energize and mobilize," he said. "They'll be there for a while."

The Democrat asked young people for small donations, building up a base of support that swelled during the campaign. "Once you get them committed, you get them bought in," Newman said.

So much of campaigns are about branding and marketing, he said.

AP exit polls found that support for Obama decreased as the age of the voters increased in Tuesday's election. Among white voters, only those younger than 30 as a group favored Obama over John McCain.

Yet, the surge of young voters didn't appear to match expectations.

Survey results showed that people under 30 comprised 17 percent of those who voted in Ohio, down slightly from four years ago.

It's possible that young conservatives were not motivated to vote this year because they saw so much enthusiasm for Obama or they thought McCain was too old, he said.

Others disagreed with the notion that young voters didn't turn out as expected. Some said there was an increase in youth turnout by at least 2 million over 2004.

"Young voters have dispelled the notion of an apathetic generation and proved the pundits, reporters and political parties wrong by voting in record numbers," said Heather Smith, the executive director of Rock the Vote.

More research is needed to determine how many young voters turned out, said Grant Neeley, a political science professor at the University of Dayton.

Exit polls, he said, could not account for the large number of young people who voted early. "That was a mobilization strategy, to get young people to vote early," he said.

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Methodology details: http://surveys.ap.org/exitpolls/