Those uncertainties have persisted into the campaign’s final hours in the wake of Monday’s release of the Des Moines Register poll.
The poll remains the most respected of Iowa surveys, in part because it accurately predicted the 2004 result.
But its conclusion that Mike Huckabee and Barack Obama hold clear leads not only contrasted with the narrow margins of other polls but was based on two stunning findings: record high turnout by independents and a strong reliance on first-time caucusgoers.
Obama’s internal polling also shows the Illinois senator ahead, according to a senior advisor in the campaign, but Clinton’s chief strategist, Mark Penn, challenged the Register’s results outright.
Most alarming, in the view of the Clinton camp, is the Register’s finding that four in ten Democratic caucusgoers will be independents.
Clinton still leads among Democrats and would win, Penn pointed out, if the 2008 independent turnout comes in at a level closer to that of previous caucuses.
In 2004, only 19 percent of Democratic caucusgoers were independents. In 2000, the figure was 17 percent, according to a CNN entrance poll. If the Register is right, 2008 would mark an historic doubling of independents participating in the Democratic contest.
The Register’s independent expectation is also roughly 10 percent larger than that of other polls, like those run by John Zogby for Reuters. Zogby’s poll, released Wednesday, finds a statistical tie between Huckabee and Mitt Romney, as well as among the three leading Democrats.
But the Register poll remains the gold standard in terms of its accuracy.
Ann Selzer, who oversees the poll, said she was surprised by the high level of independents. But she also found no reason to question her results.
“This is always the most difficult time for the pollsters,” Selzer said. “You put your faith in your method and publish and people take their shots and all you can do is sit and wait.”
And while independent turnout in the Democratic caucus above 40 percent would be surprising, it also would not be wholly illogical.
The Democratic candidates have campaigned and advertised significantly more in Iowa. The Republican candidates who appeal most to independents, John McCain and Rudy Giuliani, are hardly competing in the state.
It is not just the issue of independents that has pollsters talking. The Register poll also found that a record number of first-time caucusgoers are likely to participate.
Pollsters from Selzer to Zogby do not filter out potential caucusgoers based on whether they have previously attended a caucus. In part, this is because 45 percent of 2004 caucusgoers were first-timers, as were 46 percent of those who participated in the 2000 Democratic caucuses, according to the entrance polls.
The Register poll predicted, however, that 60 percent of Democratic participants will be attending their first caucus. It also found that new Republican caucusgoers make up 40 percent of the likely GOP voters.
These findings, however remarkable, may end up making little difference. In the last two caucuses, first-time caucusgoers voted much the same as those who had attended previous caucuses.
Some pollsters, like CBS News polling director Kathy Frankovic, question the accuracy of all surveys between Christmas and New Year’s, calling into question the Register poll as well as others released this week.
Surveys that attempt to contact people in the holiday week may miss a significant portion of residents who are traveling. Those answering may also be distracted by the holidays, Frankovic said.
The Edwards campaign caled it a “waste of money” to poll between Christmas and New Years and therefore did not, according to an Edwards’ senior advisor who spoke on the condition of anonymity.
Meanwhile, Obama’s campaign’s own internal polling has “throughout the year” tracked closest to the Register among all polls, according to a senior advisor to Obama who also asked that his name be withheld.
Despite grumbling about the poll’s findings, none of the leading Democrats disputes that it has cast the conventional wisdom for the final days before the caucuses.
Yet with the Register giving Obama a lead outside the margin of error, the onetime political upstart now faces the highest of expectations -- a bar his campaign seems to be relishing.
“It’s good to be the guy who is going into the lead in the last three or four days,” said the Obama senior advisor. “Would I want to be in this position a month out, what Hillary was in? No. Going into the last three or four days, well, that’s fantastic.”
In interviews with several leading pollsters, from the Pew Research Center’s Scott Keeter to CBS’s Frankovic, all agreed they had no reason to doubt that the Register could once more prove prescient.
The polls do nonetheless show that Obama’s strength remains particularly tenuous. He is far more reliant on high turnout among those under 34, who are traditionally least likely to turn out. Fully 72 percent of Obama’s support also comes from new caucusgoers, compared to 58 percent for Clinton and 55 percent of Edwards, according to the Register.
“If the Register is right and 45 or 46 percent of the Democratic caucuses are attended by independents and Republicans it tells you something about how good Democrats are doing and how badly the Republicans are doing as far as the general election,” said an Edwards advisor. “But there is no precedent for that.”