Iowa first step to next president

DES MOINES, Iowa (Reuters) - Voters in Iowa begin the process of choosing the next U.S. president on Thursday, and a new poll showed Barack Obama leading John Edwards in the Democratic nominating contest -- with Hillary Clinton falling to a potentially disastrous third.

The Reuters/C-SPAN/Zogby poll also showed Republican Mike Huckabee expanding his lead on rival Mitt Romney as the most heavily contested presidential caucus in Iowa history draws to a close.

For the winner in Iowa, the prize is a valuable shot of momentum and at least a temporary claim to the front-runner's slot in their party's nomination battle.

The third-place finisher in the heavyweight Democratic showdown, meanwhile, could find themselves severely wounded heading into the next contest in New Hampshire on Tuesday.

The final Reuters/C-SPAN/Zogby tracking poll before Iowa's caucus on Thursday showed Obama surging to a four-point lead over Edwards at 31 percent to 27 percent. Clinton fell to third place at 24 percent.

For Clinton, who a few months ago was declared in some quarters the almost certain Democratic nominee, a third-place finish in Iowa would be a heavy blow and would create immense pressure for a win in New Hampshire next Tuesday.

Huckabee, the former Arkansas governor whose bare-bones campaign has steadily climbed since a second-place finish at the Iowa straw poll in August, expanded his lead over Romney in the Republican race to 31 percent to 25 percent.

He took a brief break from frigid Iowa to fly to California and appear on "The Tonight Show" with Jay Leno, playing bass with the house band and crossing a picket line to appear on the show while expressing support for striking writers.

A Huckabee spokesman said he only agreed to the appearance after being assured no replacement writers were being used.

WINNOWS THE FIELD

Iowa opens the state-by-state battle to choose candidates in the November election to succeed President George W. Bush, and traditionally has served to winnow the field of laggards and elevate some surprise contenders.

The 2008 campaign is the most wide open presidential race in more than 50 years, with no sitting president or vice president seeking their party's nomination.

The Democratic caucus begins at 6:30 p.m. CST (7:30 EST), with Republicans starting 30 minutes later. Results could begin to appear within an hour or two.

Record turnout is expected for the Democrats, surpassing the 124,000 Iowans who participated in 2004. Republicans are also likely to surpass their record of 87,000 caucus participants in 2000.

Sub-freezing temperatures were predicted for caucus night, which requires Iowans to leave their homes and join their neighbors at a community gathering spot to publicly declare their support for a candidate.

In the final hours before the Thursday night caucuses, the candidates focused on driving home their message and launching a mammoth voter turnout effort.

"After all the town meetings, the pie and coffee, it all comes down to this: Who is ready to be president and ready to start solving the big challenges we face on Day One," Clinton, a New York senator, said in a paid two-minute message that aired during local newscasts.

Like Clinton, Obama also bought two minutes of air time on Iowa television stations to appeal for votes. Edwards aired a one-minute message.

"I will carry your voices to the White House and I will fight for you every day I'm there," Obama, an Illinois senator who would be the first black in the White House, said in his message.

Edwards used a laid-off Maytag factory worker from Newton, Iowa, to make the case he was the candidate who could battle corporate interests and keep U.S. manufacturing jobs.

The 2004 vice presidential candidate, who has made his promise to fight special interests the centerpiece of his campaign, ended a 36-hour marathon bus trip with a Wednesday night rally in Des Moines featuring singer John Mellencamp.

(Editing by Eric Walsh)

(For more about the U.S. political campaign, visit Reuters "Tales from the Trail: 2008" online at blogs.reuters.com/trail08/)