DES MOINES, Iowa - Republican front-runner Mitt Romney and US Representative Michele Bachmann led a closely watched presidential poll of Iowa Republicans, the state that holds the first contest in the nomination battle.

The Iowa caucuses, often held on a frigid winter night that can limit turnout to those most committed, often serve to winnow the field of candidates.

Whoever captures the nomination in the unsettled Republican field is expected to challenge Democratic President Barack Obama in the November 2012 general election.

Romney, the former Massachusetts governor, led the poll of likely caucus-goers with 23 percent, followed by 22 percent support for Bachmann, who is from neighboring Minnesota and a favorite of fiscal conservatives and the Tea Party.

Businessman Herman Cain had 10 percent support in the poll, US Representative Ron Paul of Texas and former US House of Representatives speaker Newt Gingrich followed with 7 percent. Minnesota Governor Tim Pawlenty had 6 percent, while former US Senator Rick Santorum got 4 percent and former US ambassador to China Jon Huntsman followed with 2 percent.

The Des Moines Register poll has in the past been an accurate barometer of support in the key state, and it often sets a benchmark for candidate momentum as the race takes shape. This is the first Iowa poll for the upcoming election.

The poll of 400 likely Republican caucus-goers by pollster Selzer & Co was conducted between June 19 and 22 and had a margin of error of 4.9 percentage points.

In 2008, the poll correctly predicted wins for Republican former Arkansas governor Mike Huckabee, who got support from Iowa's strong contingent of social conservatives, and Obama, who went on to win the presidency over Republican nominee John McCain.

Romney has consistently been the early front-runner in national polls for the 2012 Republican nomination but he has said he would not participate in the informal Iowa straw poll held in August. He had a disappointing second-place finish in the 2008 Iowa caucuses despite pouring resources into the race.

Iowa's first-in-the nation caucuses are widely seen as vital to the presidential hopes of Bachmann and Pawlenty of nearby Iowa.

Bachmann was set to formally announce her candidacy on Monday in Waterloo, Iowa, where she spent her early childhood.

Last weekend, Texas' Paul won a non-binding preference poll at a Republican conference in New Orleans. Huntsman joined the field last week but said he will not campaign in Iowa, betting on a good showing in New Hampshire's primary roughly a week later.

The Republican field may expand, with the intentions of former Alaska governor Sarah Palin and Texas Governor Rick Perry unknown.

Reuters