Pollsters struggle to explain Clinton win

— -- A day after Hillary Rodham Clinton's surprise victory in the New Hampshire primary, the country's leading political pollsters found themselves trying to explain how and why they got it so spectacularly wrong.

Although most pre-election voter surveys accurately predicted Republican John McCain's win, most had Barack Obama crushing Clinton in the Democratic race. The average spread was 8.3 percentage points, according to the RealClearPolitics website. A USA TODAY/Gallup Poll published Monday had Obama leading by 13 points.

Even early surveys of people after they voted had Obama winning by 5 points. But when the votes were counted Tuesday night, Clinton won with 39% to Obama's 36%.

Pollsters came forth Wednesday with explanations that were part mea culpa, part admonishment that certain elections are simply impossible to predict.

Some, including Gary Langer, polling director for ABC News, called for an independent panel of experts to investigate what happened.

Some pollsters said the record-shattering turnout may have produced a different electorate than the one envisioned in their models designed to predict who will vote. Others pointed to the surveys as voters left the polls showing that 17% made up their minds on primary day, which they said may have confounded the pre-election surveys.

"It's absolutely a cautionary tale to both the people who do polls and the people who read polls," said Richard Morin, a public-opinion expert at the Pew Research Center. "Pre-primary polling is fraught with dangers. That is particularly the case in New Hampshire, which I have called the graveyard of political pollsters."

Andy Smith, a pollster for the University of New Hampshire, noted that previous pre-election polls in New Hampshire have gotten the margins wrong, underestimating, for example, McCain's 18-point defeat of George W. Bush in the 2000 GOP primary. Smith's final poll, for CNN, had Obama up by 9 points.

Usually, the vast majority of pre-election polls get the result right, said Langer, who did not conduct a New Hampshire poll after the Iowa caucuses, when most surveys began showing large Obama leads.