Sen. Barack Obama, D-Ill., Democratic presidential hopeful, points to the crowd after speaking at a campaign stop Wednesday in Des Moines, Iowa.

Former Arkansas Gov. Mike Huckabee, Republican presidential hopeful, speaks Monday during a news conference in Des Moines, Iowa.

Des Moines, Iowa ? Sen. Barack Obama swept to victory in the Iowa caucuses Thursday night, pushing Hillary Rodham Clinton to third place and taking a major stride in a historic bid to become the nation’s first black president. 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.

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 Democratic returns showed the first-term lawmaker gaining 37 percent support. Former Sen. John Edwards of North Carolina gained second, barely edging out Clinton, the former first lady.

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.

Nearly complete returns showed Huckabee with 34 percent support, compared with 25 percent for Romney. Former Sen. Fred Thompson and Sen. John McCain battled for third place, while Texas Rep. Ron Paul wound up fifth and former New York Mayor Rudy Giuliani sixth.

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

Edwards, the Democrats’ 2004 vice presidential nominee, told The Associated Press in an interview 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. “I’m going to fight for that change,” he said by telephone from his hotel room in Iowa. “I’ve fought for it my entire life. I have a long history of fighting powerful interests and winning.”

Projections estimated that 220,588 Democrats showed up on a cold midwinter’s night, shattering the previous mark of 124,000.

Turnout was also up on the Republican side, where projections showed about 114,000 people taking part. The last previous contested Republican caucuses in 2000 drew 87,666 participants.