The P-I's Strange Bedfellows blog recently posed the question: "Has Giuliani locked up the GOP nomination?"

In answering the question, the post relies on a Pew study that examines in part the value of early national polls in predicting Presidential Primary winners. The blog leans toward giving Rudy Giuliani a forecasted win based on his "dominating the polls on the Republican side."

Giuliani is in a strong position currently, despite a recent stumble or two. But here's a better idea: ignore the national polls.

Mark Blumenthal at Pollster.com has done some fantastic analysis as of late on understanding the Presidential primary process and the polls that cover it. He recently found a stark discrepancy (with more here) between who gets surveyed in national primary polls versus those who actually participate in Presidential primaries and caucuses:

Thus, for the Democratic primary preference for example, national surveys are reporting the views of 35% to 55% of their adult samples that identify as Democrats or Democratic "leaners" when the people we really care about - those whose votes will ultimately choose the nominee - are likely to amount to less than 10% of adults.

This raises serious questions about the value of early polls.

Looking back on the 2004 Democratic primary, the most recent, competitive such contest, shows an interesting lack of correlation between the early national polls and the actual results. Fall 2003 polls from Zogby and Marist College showed John Kerry and John Edwards buried deep in the pack. So too did a December 2003 poll from CBS.

Polls in the early states of Iowa and New Hampshire were more helpful as the contests approached. Assorted pre-caucus polls in Iowa showed Howard Dean in the lead before catching a late shift toward John Kerry. In New Hampshire, polls showed Dean in the lead until the results of the Iowa caucuses took over the news cycle; then it was all Kerry.

The bigger trend to notice is the profound impact of the outcomes in Iowa and New Hampshire on the national race. Blumenthal taps some in-depth, post-2004 analysis revealing the startling reversal in national polls based on the results in those early states:

Just before Iowa, according to the ANES data, only 9% of those planning to vote in the Democratic primaries or caucuses nationally supported Kerry. Kerry shot up after his Iowa caucus victory, approaching 50% in the week before New Hampshire and hitting 68% by the end of February. At the same time, Howard Dean's support collapsed, falling from 31% in early January to near zero by March, while John Edwards, who finished a surprisingly strong second in Iowa, saw his national support grow from 5% to 25%.

The graphic here shows just how profound the shift was.

Why? Blumenthal says the early contests

effectively winnow the field. While news accounts may emphasize the large field of candidates before the early primaries (with an emphasis on front-runners), the coverage afterwards focuses far more intensely on the early winners. The result is that also-ran candidates either drop out entirely, or effectively drop out of site, a process that simplifies voter choices.

Furthermore,

the horse race nature of the coverage leads voters to more positive evaluations of the winners and more negative evaluations of the losers. Media accounts portray the winners and their campaigns as competent and able, while the losers look hapless and faltering. Which set of characteristics would you want in a president?

Each Presidential primary process is unique, plus they occur infrequently enough it's difficult to infer many standing rules for how they will unfold. Yet, the last competitive primary in anything near the 24-hour news cycle now the norm in America showed pre-primary national polls to have almost no predictive value.

Maybe Giuliani is primed to secure the nomination. He's the front-runner for now. And sure, national polls are great sport for political junkies to track, especially in the modern, information-hungry news environment. But those interested in who is actually going to be nominated by either party may want to keep a closer eye on Iowa and New Hampshire in the coming months than on Gallup and company.

**Note: a great resource for 2008 polls at the national and state level is available from RealClearPolitics.

UPDATE: link fixed.