Sen. Barack Obama swept to victory in the Iowa caucuses Thursday night, pushing Sen. Hillary Clinton to third place and taking a major stride in a historic bid to become the nation's first black president. And Mike Huckabee rode a wave of support from evangelical Christians to win the opening round among Republicans in the 2008 campaign for the White House.

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Obama, 46 and a first-term senator from Illinois, told a raucous victory rally his triumph showed that in "big cities and small towns, you came together to say, 'We are one nation, we are one people and our time for change has come.'"

Final returns showed Obama gaining 37 percent support. Former Sen. John Edwards of North Carolina appeared headed for second place, relegating Clinton, the former first lady, to a close third.

The cold winter night in Iowa couldn't keep caucus-goers from shattering previous turnout marks.

On the Democratic side, turnout was estimated at 239,000 people. That breaks the previous mark by more than 100,000 participants.

Republican turnout was up sharply as well.

The spike in attendance was attributed by observers in part to a wide-open race that didn't include an incumbent or a sitting vice president.

Some poll watchers had feared that the crush of participants would delay the process, but things appeared to have gone smoothly.

Huckabee celebrated his own victory over Mitt Romney and a crowded Republican field.

"A new day is needed in American politics, just like a new day is needed in American government," the former Arkansas governor told cheering supporters. "It starts here but it doesn't end here. It goes all the way through the other states and ends at 1600 Pennsylvania Avenue."

Huckabee, a preacher turned politician, handily defeated Romney despite being outspent by millions of dollars and deciding in the campaign's final days to scrap television commercials that would have assailed the former Massachusetts governor.

His triumph more robust than Obama's, he won 34 percent support, compared to 25 percent for Romney. Former Sen. Fred Thompson and Sen. John McCain battled for third place.

Losers Vow Fight

With the New Hampshire primary only five days distant, Clinton and Edwards vowed to fight on in the race for the Democratic nomination.

Not everyone was going on. Officials said Democratic Sens. Christopher Dodd of Connecticut and Joseph Biden of Delaware were leaving the race after failing to generate appreciable support in Iowa.

Clinton hailed what she called a "great night for Democrats" and said the strong turnout pointed for sure to the election of a Democratic president in November. She said she would "keep pushing as hard as we can."

The former first lady, who had once held a commanding lead in polls here, congratulated Obama and Edwards. She promised cheering supporters she would take "this enthusiasm and go tonight to New Hampshire." The state holds its primary on Jan. 8.

"We're going to keep pushing as hard as we can," she said. Supporters chanted, "Hillary, Hillary."

With former President Bill Clinton and their daughter, Chelsea, standing to one side of her and former Secretary of State Madeleine Albright to the other, Clinton said, "I am so ready for the rest of this campaign and I am so ready to lead."

"This is a great night for Democrats," she said. "We have seen an unprecedented turnout here in Iowa and that is good news because today we are sending a clear message that we are going to have change and that change will be a Democratic president in the White House in 2009."

Edwards told The Associated Press that the Iowa caucus showed that voters are choosing change over the status quo, and he vowed a vigorous campaign into New Hampshire.

Edwards: 'Grossly Outspent'

Edwards said he would continue running as the candidate for middle-class Americans. Edwards finished second and Clinton was a close third.

"I mean, we were grotesquely outspent in Iowa 5-to-1 and the fact that I'm as strong as I am now under these circumstances indicates that this message of change and standing up to corporate greed and fighting for the middle class and jobs really matters," the 2004 vice presidential nominee said in an interview with The Associated Press.

He said he would distinguish himself from Obama in New Hampshire by arguing that he is the candidate who can deliver the change that voters have shown they want.

"What's clear from the Iowa caucus results is that change won and the status quo lost," Edwards said via telephone from his hotel room in Iowa.

Romney failed Thursday to pick up the first of two back-to-back wins he hoped would propel him toward his party's presidential nomination, despite having spent more time and money in Iowa.

During the past two months, Romney surrendered a double-digit lead in the polls, in part on the strength of Christian conservative support for Huckabee. Romney, trying to become the first Mormon president, has faced questions from some evangelicals who consider his faith a cult.

Romney: 'Won The Silver'

After being introduced by Dan Jansen, the speed skater who competed in four Olympic Games before winning a gold medal, Romney said in his concession speech: "Well, we won the silver and congratulations to Gov. Huckabee for winning the gold. Nice job."

Romney added: "You win the silver in one event, it doesn't mean you're not going to come back and win the gold in the final event, and that we're going to do."

Romney insisted the Iowa results - with outsiders like Huckabee and him finishing one-two and freshman Illinois Sen. Barack Obama winning on the Democratic side - showed voters want change in Washington.

"We need new faces in Washington, and I intend to be one of them," Romney said.

Giuliani praised rival Huckabee for his win in the Iowa caucuses on Thursday -- a contest Giuliani essentially skipped -- yet insisted his own early-state campaign could win over the long haul.

"I think we're in good shape. We're ahead in maybe 16, 18 of the 29 states that are coming up," the former New York mayor said. "This was the first one. I think it's one that, quite honestly, we didn't expect that we would win. And we didn't put a lot of resources into it. And now we'll move on to the others."

Giuliani holds an early lead in polls in Florida, which conducts its primary Jan. 29, and said he hopes a strong showing there will offset poor results in early-voting states.

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