Jeffrey D. Allred, Deseret Morning News
Supporters of Sen. Barack Obama, including Eric Kiltz, left, cheer as they watch the results from Iowa on Thursday in Salt Lake City.

DES MOINES, Iowa — Sen. Barack Obama of Illinois, a first-term Democratic senator trying to become the nation's first African-American president, rolled to victory in the Iowa caucuses on Thursday night, lifted by what appeared to be a record turnout of voters who rejected the criticism that he did not have enough experience.

"They said this day would never come. They said our sights were set too high. ... But on this January night, on this defining moment in history, you have done what the cynics said we couldn't do. You did what the state of New Hampshire can do in five days," Obama said.

Obama's victory amounted to a significant setback for Sen. Hillary Rodham Clinton of New York, who just months ago appeared to be the front-runner for the Democratic presidential nomination but has watched her position erode over the past several months. The result also left uncertain the prospects for John Edwards, a former senator from North Carolina, who had staked his second bid for the White House on winning this state.

Candidates Sen. Joe Biden, D-Del., and Sen. Chris Dodd, D-Conn., announced they are dropping out of the race due to their poor showing in Iowa.

On the Republican side, Mike Huckabee, the former governor of Arkansas who was barely a blip on the national scene just two months ago, defeated Mitt Romney, a former Massachusetts governor, delivering a serious setback to Romney's high-spending campaign and putting pressure on Romney to win in New Hampshire next Tuesday.

Huckabee won with 34 percent of the vote, after 65 percent of precincts had reported. Romney had 24.9 percent, former Sen. Fred Thompson of Tennessee had 13.7 percent and Sen. John McCain of Arizona had 13.2 percent.

On the Democratic side, with 80 percent of precincts reporting, Obama had 36.3 percent, Edwards 30.5 percent and Clinton had 30.2 percent. Gov. Bill Richardson of New Mexico was fourth, at 1.9 percent.

A record number of Democrats turned out to caucus, producing scenes of overcrowded firehouses and schools and long lines of people waiting to sign in. Obama's victory in this overwhelmingly white state stood as a powerful answer to the question of whether America was prepared to vote for a black person for president. At the same time, the apparent surge of independent voters to his side, as suggested by polls of voters entering the caucuses, suggested his potential appeal in a general election.

The result sent waves of apprehension across Clinton's camp, and she turned her attention to New Hampshire. Aides said that former President Bill Clinton would go there immediately and spend the next five days campaigning in a state where he has always been strong.

On the Republican side, Romney had blanketed the state with television advertisements and, with a nod to the way campaigns are normally won here, built an extensive get-out-the-vote operation that carted Romney's supporters to the polls all days. As polls showed Huckabee rising, Romney responded with a month-long barrage of ads attacking him on immigration and taxes.

"Congratulations on the first round to Mike," Romney said on Fox News.

Huckabee's populist appeal — powered by support from evangelicals — out-muscled a political operation that Romney spent more than a year building. Polls of Republicans entering the caucus sites found that nearly 60 percent described themselves as evangelical, and by overwhelming numbers they said they intended to vote for Huckabee.

A survey of Democrats entering the caucus sites found that more than half said they were attending their first caucus — and they divided with about 40 percent for Obama and about 30 percent for Clinton.

There was also a sharp generational break in support of the two candidates. Obama was backed by 60 percent of voters under 25 while Clinton was supported by about 45 percent of voters over 65.

Among Democrats, nearly half of respondents said that their top factor in choosing a candidate was someone who could bring about change; Obama won the support of about half that group. Just 20 percent said the right experience, Clinton's key argument, was the main factor; among that group, nearly half chose Clinton.

For all the talk about electability, barely one in 10 respondents said it was the main factor in their decision. Clinton and Edwards had an edge over Obama in this area.

Among Republicans, 6 in 10 described themselves as evangelical Christians; they went overwhelmingly for Huckabee. Huckabee was also supported by more than half of the Republican caucus-goers who said it mattered a great deal that a candidate shared their religious beliefs.

The personal quality Republican voters said mattered most in a candidate was that they shared their values. What mattered second most was that a candidate said what he believed. Huckabee outpolled Romney in both of those groups.

The Republican race was relatively straightforward. Romney and Huckabee were the main contestants, with none of the other candidates devoting much time or money to the state. Former New York Mayor Rudolph Giuliani made intermittent efforts here. McCain at one point all but wrote off the state, but returned after he won the endorsement of The Des Moines Register and saw, with the rise in polls of Huckabee, an opportunity to finish third.

For Democrats, the contest had historic overtones: a battle between a first-term senator, Obama, trying to become the nation's first black president, and a former first lady, Clinton, seeking to become the first woman to occupy the Oval Office.

From the start, Obama and Clinton drew huge crowds as they laid out decidedly different appeals. Clinton presented herself as the candidate of experience; Obama presented himself as the candidate of change.

This is Edwards' second bid for the presidency. In 2004, he placed second in Iowa. Although he, too, drew big crowds, he frequently found himself crowded out by the fight between . Clinton and Edwards as he presented an increasingly hard-edged, populist message.

The Democratic caucus results do not reflect the actual percentage of people who expressed a preference for a particular candidate. Rather, they are the percentage of delegates allocated to each of the candidates based on a complex formula; the Democratic Party does not release the actual number of Democrats who caucus for each candidate.

The Republican results reflect a direct count of the preferences expressed by those who participated in the Republican caucuses.

Mirroring the unusual rush of the nominating calendar — the primary in New Hampshire is a mere five days away — the major candidates planned to pack up as soon as the caucus results were known and fly to New Hampshire to be on the ground for early-morning rallies, television appearances and campaign stops. Clinton's campaign plane was scheduled to leave Iowa at midnight.

The one exception was Giuliani, who largely skipped the Iowa caucuses; he started the day in New Hampshire and spent the rest of it in Florida.

A wide-open race in both parties sparked a record turnout Thursday in Iowa's caucuses, far exceeding previous contests.

Projections showed a turnout of 220,588 for Democrats, compared to 124,000 who participated in 2004. Most projections had estimated turnout would be about 150,000.

Turnout was also up on the Republican side, where projections showed about 114,000 people taking part.

The last contested Republican caucuses in 2000 drew 87,666 in caucuses won by then-Gov. George W. Bush.

The voting on Thursday ended what was one of the most intense years of politicking in the history of the Iowa caucuses. Television advertisements for all the major candidates were aired right up until the time Iowans were leaving their homes — or being picked up — for the start of the caucuses.

As the day moved on, the candidates and some spouses — like Bill Clinton — were doing interviews with Iowa television and radio stations. The campaigns, meanwhile, began executing the most sophisticated voter turnout operations ever seen in Iowa as campaign workers began calling people who had been identified as supporters to make certain they would show up to make their preferences known.

The inducements included free rides to caucus sites, baby-sitting and food. In a development that both Obama and Clinton had hoped for, the day was snow-free and the single-digit temperatures from earlier in the week were gone. The theory was that supporters of Edwards were experienced caucus-goers who were used to dealing with bad weather; Obama had sought to expand the universe of caucus-goers by appealing to young voters, while Clinton was looking for first-time caucus-goers among younger women and women over 65.

Contributing: Amy Lorentzen, Associated Press