| DES MOINES, Iowa
DES MOINES, Iowa Democrat Hillary Clinton holds a narrow lead in Iowa four days before the state opens the presidential nominating race, while Republicans Mike Huckabee and Mitt Romney are virtually tied, according to a Reuters/C-SPAN/Zogby poll released on Sunday.
Clinton, a New York senator, led Sen. Barack Obama of Illinois 31 percent to 27 percent, with former North Carolina Sen. John Edwards a close third at 24 percent and no other Democratic contender registering in double-digits.
Huckabee, a former Arkansas governor, held a statistically insignificant one-point edge over former Massachusetts Gov. Mitt Romney, 29 percent to 28 percent. Arizona Sen. John McCain was a distant third with 11 percent.
Three Republicans, former Tennessee Sen. Fred Thompson, former New York Mayor Rudy Giuliani and Texas Rep. Ron Paul, registered 8 percent in the poll.
The poll found about 6 percent of likely caucus-goers in each party are uncertain of their choice in Thursday's contest, the first big test in the state-by-state battle to choose candidates for the November presidential election.
"We have two very tight races that are too close to call," said pollster John Zogby. "But there is a lot of potential for things to change here."
The poll of 934 likely Democratic caucus-goers and 867 likely Republican caucus-goers was taken Wednesday through Saturday and has a margin of error of 3.3 percentage points for the Democrats and 3.4 percentage points for the Republicans.
CLINTON'S NARROW EDGE WITH WOMEN VOTERS
Clinton, Obama and Edwards have battled for the Democratic lead for months in Iowa, where a win can generate huge momentum for later contests. The new poll showed Clinton, who would be the first woman in the White House, narrowly leading Obama among women voters and ahead among older voters, who are the most likely to participate.
Obama, who would be the first black president, held a big lead among younger voters, whose participation is more unpredictable.
Delaware Democratic Sen. Joseph Biden and New Mexico Gov. Bill Richardson each earned 5 percent, with Connecticut Sen. Chris Dodd at 1 percent and Ohio Rep. Dennis Kucinich below 1 percent.
The poll found Clinton's supporters were the most dedicated, with 76 percent saying their support was "very" strong, compared to 65 percent for Edwards and 56 percent for Obama.
Under Iowa's arcane caucus rules, candidates must receive support from 15 percent of the participants in each precinct to be viable. If not, their supporters can switch to other candidates.
Edwards was the most popular second choice with 30 percent, while Obama had 25 percent and Clinton only 12 percent.
Among Republicans, where Huckabee's recent surge to the top of many Iowa polls has been fueled by support among religious conservatives, the former Baptist preacher led among those who said they were "very" conservative, and born-again Christians.
About half of Romney and Huckabee's supporters described their backing as "very" strong.
The race for third among Republicans is wide open between McCain, Thompson, Giuliani and Paul, all of whom could take some solace from a strong finish and hope to generate momentum for the next contests.
McCain and Giuliani have barely competed in Iowa, preferring to focus on New Hampshire and a big round of contests on February 5, respectively. Thompson largely ignored the state until launching a final push here in the week before Christmas.
The rolling three-day tracking poll will continue each day through the Iowa caucus on Thursday.
(Editing by Todd Eastham)
(For more about the U.S. political campaign, visit Reuters "Tales from the Trail: 2008" online at blogs.reuters.com/trail08/)