New Hampton, Iowa ? Hillary Rodham Clinton has taken the lead among Democratic presidential candidates in an Iowa poll, an encouraging sign of progress toward overcoming a big hurdle in the race.

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 John Edwards and Barack Obama 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.

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.