Obama won 57 percent of the vote among Democrats under age 30 in Thursday's first-in-the nation caucuses, CNN reported.

That helped him secure 38 percent of the vote overall, to 30 percent for former South Carolina Sen. John Edwards and 29 percent for second-term New York Sen. Hillary Clinton.

Two candidates -- Delaware Sen. Joe Biden and Connecticut Sen. Chris Dodd -- scarcely registered with caucus goers and announced they would drop out of the presidential nomination race.

New Mexico Gov. Bill Richardson finished fourth with 2 percent and said he would "take the fight to New Hampshire," which holds the first-in-the-nation primary election next Tuesday.

The Iowa Democratic Party said the turnout for the caucuses was a record, with at least 227,000 voters participating, CNN reported. That compares with a turnout of 124,000 in the 2004 caucuses.