With less than 48 hours to go to Monday's showdown, amid predictions of record turnouts, the race is too close to call in this Midwestern farm state.
Most polls show Senator John Kerry, former Vermont governor Howard Dean, Richard Gephardt, the former Democrat leader in the House of Representatives, and Senator John Edwards in a neck-and-neck race for the finish line.
All four barnstormed across the state on Saturday in search of the few votes that could determine victory and a crucial advantage heading into caucuses and primary elections across the United States.
"This is going to be a close election," Missouri congressman Gephardt told supporters at a rally in Davenport, Iowa. "It could be decided by one vote in each precinct."
The candidates have poured money and campaign volunteers into Iowa in search of an early victory that could give them momentum going into the New Hampshire primary on 27 January and even more importantly "Super Tuesday" on 2 March when 10 states hold their contests.
While Dean appeared to have a lock on first place there for a long time, that edge has eroded in recent days, according to polls, and the latest sampling of public opinion gives Kerry the edge.
A Des Moines Register poll, to be published on Sunday, puts Kerry 3% in advance of his closest rival, John Edwards, with 26%. Dean had 20% and Gephardt, 18.
Pundits have cautioned against placing too much stock in the polls, given the unpredictable nature of the caucuses and the large number of undecided voters.
Much will hinge on turnout, given the small numbers of voters that participate in the Hawkeye's quirky selection process, and that is what candidates were focusing on Saturday.
"We are going to find out if we can convert this unbelievable grass-roots movement into votes," Dean told his supporters at a rally Saturday.
The Dean campaign, which has taken the national Democratic Party by surprise with its phenomenal internet-based success in fundraising and mobilisation, has flooded the state with thousands of volunteer campaigners.
Filmmaker Michael Moore (L)
supports retired Gen Wesley Clark
Gephardt has experienced union strategists running a slick get-out-the-vote operation concentrating on union workers, leaving Gephardt to focus on other voters.
Kerry and Edwards appear to have made strides in the waning days of the campaign by staying away from the negative campaigning, favoured by Dean and Gephardt.
"We don't believe in tearing people apart, we believe in bringing 'em together," Edwards said at one stop on Saturday.
Vietnam veteran Kerry got a boost from a piece of campaign theatre on Saturday, when a Green Beret who Kerry rescued in Vietnam came forward after an absence of years to personally endorse the senator.
"I haven't talked to this guy since March of 1969 ... but he is going to get my vote," said Jim Rassmana as he embraced Kerry at a stop in Des Moines.
Kerry continues to target
the current White House incumbent
"After watching him in the Senate all these years, I have no doubt that he is going to make an excellent president."
Kerry continued to target the current White House incumbent.
"George Bush is taking America in a radically wrong direction, and we are going to turn it around," he said.
But whoever wins the nomination, to be formally decided at a national convention in Boston in July, faces a battle in the November general elections.
President George Bush has been buoyed recently by the capture of former Iraqi president Saddam Hussein, and signs of a strengthening economy.
He is unchallenged and has amassed a campaign war chest of more than 130 million dollars.
"By the time they get through slaughtering each other's characters... you begin to wonder if you're voting for the right person"
Bush spent the weekend at his presidential retreat at Camp David in Maryland, preparing his annual State of the Union speech to Congress on Tuesday - his last before the 2 November poll.
In the months before then, the Democrats will likely continue to attack each other as they jockey for an edge before the Democratic convention in July.
Dean supporter Teresa Valyer, a teacher from Council Buffs, said she was already weary of the negative campaigning.
"By the time they get through slaughtering each other's characters," she said, "you begin to wonder if you're voting for the right person."