Barack Obama said today his message of hope and change resonated with young people and sparked record numbers to help propel him past Hillary Clinton to win Iowa's Democratic caucus.
Mr Obama, a first-term senator from Illinois, said there had been scepticism that many people would actually participate in yesterday's Democratic caucus.
Barack Obama
"So it really was a victory for the people of Iowa," Mr Obama told reporters after his victory over Ms Clinton and former North Carolina senator John Edwards. "I think it's a harbinger of what's going to happen around the country."
Mr Obama (46), said his message of hope and a desire for change hit home with Iowans, encouraging many to vote for the first time.
"I really think that the country is interested not just in change in the abstract but in the very specific kind of change which involves them getting involved, paying attention, holding their elected officials accountable," he said. "That was reflected, I think, in the results."
Mr Obama and his aides said that record turnout - about 239,000 Democrats voted, up from 124,000 in 2004 - and strong support among women and young people helped push him to victory.
Mr Obama beat Ms Clinton among women by five percentage points. In addition, about 57 per cent of voters under 29 years old voted for Mr Obama, and they represented 22 per cent of the total vote.
The next primary will be held in New Hampshire in five days.