DES MOINES, Iowa (CNN) -- In the final hours before the Iowa caucuses, candidates are trying to gain the support of the undecided and make sure their supporters show up.
Hillary Clinton speaks to supporters in Iowa City, Iowa, on Tuesday.
Three Democrats and two Republicans are virtually tied at the top, according to the latest CNN/Opinion Research Corp. poll, and last-minute decisions from undecided voters could push a candidate to the head of the pack.
This week's poll shows that 17 percent of likely Democratic caucus-goers said they are still trying to decide which candidate to support, and more than a quarter of Republican caucus-goers said they are still trying to decide.
The White House hopefuls are taking different crunch-time approaches as they try to woo Iowans one day before they head out to vote.
Former North Carolina Sen. John Edwards, who has been on a 36-hour tour through Iowa, attended a rally around midnight and made stops throughout the morning Wednesday.
Edwards has been trying to convince voters that his passion for change comes from the heart, saying he is the one who is going to help the little guy more than the others. Watch how Democratic candidates are spending the final hours »
The campaign for Hillary Clinton has been focusing on portraying her as the candidate with experience. The New York senator's camp has passed out door hangers telling people the stakes are high and they have to vote.
While Clinton's campaign is telling voters she has the track record to make good on her promises, the campaign for Sen. Barack Obama of Illinois is telling voters to hope for something different.
In telling Iowa voters that their first-in-the-nation caucus give them "extraordinary privilege," Obama emphasized to Iowa voters that he would be a candidate who would bring about a new style of politics. See photos of the candidates campaigning on Wednesday »
Campaigns were working to finalize massive get-out-the-vote efforts to get their supporters to the caucuses Thursday.
The Clinton campaign was distributing hundreds of shovels to help clear the sidewalks of supporters which may be key to getting the first-time caucus-goers out. The Obama camp is organizing baby-sitting services for its supporters.
While all of the Democratic candidates were in Iowa on New Year's Day, the Republicans were spread across the country, possibly reflecting the fact that the Iowa contest has come down to a race between Mike Huckabee and Mitt Romney.
After a lot of talk of negative campaigning, the front-runners are emphasizing their biographies and what they would do as president.
Romney's camp, however, is focusing on the voters who have committed to him and not those who are still undecided. Watch how GOP candidates are courting the undecided »
The former Massachusetts governor has an extensive computer database and his campaign is calling supporters to make sure they get to the caucus.
Romney told CNN Wednesday he is confident of his chances in Iowa, but would be happy with either a first- or second-place showing in the Hawkeye State. Watch what Romney says about his Iowa work »
Huckabee, who doesn't have the funds and organization of his chief rival, is relying on the passion among evangelicals and the coalitions who support him to push him ahead Thursday.
Romney leads with the backing of 31 percent of likely Republican caucus-goers and Huckabee has 28 percent. Former Tennessee Sen. Fred Thompson has 13 percent, followed by Arizona Sen. John McCain with 10 percent, according to the CNN/Opinion Research poll released Tuesday.
In the Democratic race, the poll shows Clinton and Obama essentially tied for the lead in Iowa. The poll shows 33 percent of likely Democratic caucus-goers backing Clinton and 31 percent supporting Obama. Edwards is in third place in the poll at 22 percent.
The survey has a margin of error of plus or minus 4.5 percentage points in the Democratic race and 5 percentage points on the GOP side, meaning the race is virtually tied on both sides. E-mail to a friend
CNN's Jessica Yellin and Dana Bash contributed to this report.