Although the New York senator is the clear front-runner in national surveys, Iowa has remained an elusive prize. She has been in a tight race with and in the state that begins the primary campaign voting in three months.
But her campaign has focused on boosting her appeal in Iowa, including two visits with her husband, former President Clinton, by her side over the summer. The effort appears to have paid off, according to the poll of likely Iowa caucus-goers that was published in Sunday's Des Moines Register.
Clinton was supported by 29 percent of the 399 respondents to the poll conducted Oct. 1-3, compared with 21 percent in May.
Edwards and Obama are not far behind, ensuring that all three campaigns will continue their intense efforts in Iowa, which leads off voting in the 2008 primary contests.
"I'm doing everything I can to earn the support of Iowans," Clinton said during a stop in New Hampton. A standing room only crowd at a community center was warmed up by listening to disco hit "Ain't No Stoppin' Us Now."
"I pay absolutely no attention to what any poll says or what any pundit on TV says," the former first lady said. "I have absolutely no interest in that. Nobody has come to a caucus yet. Nobody has cast a vote yet."
CBS News correspondent Joie Chen reports that Clinton's lead has led her rivals to sharpen their attacks. A new Obama television ad has a retired general criticizing Clinton's vote for the Iraq war.
While Clinton visited small towns in eastern Iowa, Edwards was in the midst of a four-day tour of the state that included stops in 17 counties. The new poll showed his support falling from 29 percent, good enough for first place in May, to 23 percent. That is a statistical tie with Obama's 22 percent.
The poll has a margin of error of 4.9 percentage points.
Edwards told reporters in Davenport that he sees it as a close three-way race, with his two chief rivals rising recently because "they spend millions of dollars on television advertising."
"But, I think it's much more important to Iowa caucus-goers to see you in the flesh - see you stand before them, look them in the eye and answer their hard questions," the former North Carolina senator said.
Clinton got one of those hard questions in New Hampton, and it led to a heated exchanged.
Randall Rolph of Nashua challenged her for voting last month to designate Iran's Islamic Revolutionary Guard Corps a terrorist organization. Some Democrats said they feared that such a designation could be interpreted as a congressional authorization of military force in Iran.
Rolph compared Clinton's vote on the Iran measure with her vote to authorize war in Iraq. "It appears you haven't learned from your past mistakes," he said.
Clinton responded that his interpretation was wrong and suggested that someone put him up to asking the question. The man said he did his own research and was offended that she would accuse him of getting it elsewhere. She apologized but insisted he must be looking at the wrong version of the bill.
Their exchanged grew heated as he insisted the bill would authorize combat. Clinton snapped back, her voice rising, "I'm sorry, sir, it does not."
"I know what we voted for, and I know what we intended to do with it," she said. She said it gives the authority to impose penalties.
Many in the crowd applauded her in an effort to cut off the exchange, although afterward at least a couple others in the room came up to thank Rolph. He said he is still undecided about which Democrat he will support, but it will not be Clinton.