First off, I don’t accept your comparison of Tom Harkin to Mitt Romney. By the time of the ‘92 Iowa caucuses, Harkin had served 10 years in the House and one term+ in the Senate (he was re-elected to his second term in ‘90). In these 18 years (‘74-’92) in office, Harkin had built up a very strong organization in the state; it helped him knock off an incumbent in ‘84 to get to the Senate and to put down a well-funded challenger (former Rep. Tom Tauke) to win re-election in ‘90. Comparing this to a one-term governor from a different state (albeit one that has a significant media/cultural reach across the border) just doesn’t hold up. What’s more, how is McCain going to “write off” the state that did much to make him who he is today politically? Ceding a state that you won by 19% last time is not realistic.
You’re right, though, New Hampshire does have a history of rewarding GOP insurgents; Buchanan even got significant chunk of the vote against a sitting prez in ‘92. So lets look at the two other major states, Iowa and South Carolina. Would you argue that McCain and Giuliani are likely to fare better there, in contests dominated by social conservatives, than in New Hampshire?
Florida or California, of course, could jumble the mix, but each of the three traditional first states are, last time I checked, pretty passionate about keeping their position at the head of the line and will likely do what it takes to remain there.
As for the polling, of course HRC, McCain and Giuliani are among the leaders. Who else would be in a national poll in December of ‘06?