Voters in Iowa begin the process of choosing the next U.S. president on Thursday with two close nominating races, as a new poll showed Barack Obama leading John Edwards among Democrats -- with Hillary Clinton falling to a potentially damaging 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. However, polls in Iowa are particularly difficult since fewer than 250,000 of the state's almost 3 million residents are likely to vote.
Other polls show both races even tighter in the final hours before Iowa opens the state-by-state battle to choose candidates to succeed President George W. Bush -- a process that will climax in the November 8 presidential election.
The Democratic caucus begins at 6:30 p.m. CST (12:30 a.m. British time), with Republicans starting 30 minutes later. Results could begin to appear within an hour or two.
Candidates hit the trail on Thursday for a few final rallies before the evening caucuses, focusing on driving home their message to undecided voters and launching a mammoth voter turnout effort.
"We are going to prove that our campaign to stand up for the middle class and stop corporate greed in America is unstoppable," Edwards, a former trial lawyer and North Carolina senator, said at a rally for steelworkers and campaign volunteers in Des Moines.
For the winner in Iowa, the prize is valuable 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 hobbling heading into the next contest in New Hampshire on Tuesday.
The final Reuters/C-SPAN/Zogby tracking poll showed Obama, running to become the country's first black president, holding a statistically insignificant four-point lead over Edwards at 31 percent to 27 percent.
Clinton, the former first lady who would if elected be the country's first female president, slipped to third place at 24 percent. The survey carries a statistical margin of error of plus or minus 3.3 percentage points.
For Clinton, who a few months ago was considered in some quarters the almost certain Democratic nominee, a third-place finish in Iowa would create immense pressure for a better performance in New Hampshire next Tuesday.
