From Politico

The Des Moines Register hasn’t released all the numbers from its last poll, but one thing’s pretty clear: This is a turnout story, not a story of people changing their minds. Obama’s gains appear to have been driven by independents saying they plan to attend Democratic caucuses and support him.

Relying on people who have never voted before, or have never voted in a party caucus/primary before, is a risky strategy. Just ask John McCain after Michigan in 2000, and Howard Dean after Iowa in 2004. Anyhow, that’s nothing new, and Obama’s campaign team already knows what needs to be done

But it also adds to the pressure on the ground game. As I’m told Obama’s Iowa director, Paul Tewes, warned his staff last night, “polls are sh**.”

Then he told them not to drink too much, because they’re all working today.

I presume most committed Iowan caucusers are used to the cold, and short of a record blizzard, mere average winterly temperature won’t keep them at bay. Whether or not less committed Iowa independents are as weather hardened is yet to be seen (it’s supposed to reach the mid teens Thursday night, but remain pleasantly mostly clear). I’m sure the Obama grass roots operators will find out soon enough. Dutifully plugging for irony, this may be the only time in Hillary Clinton’s Democratic career that she will be praying for precipitation.

If Obama’s ground team achieves the extraordinarily hard task of getting sufficient independent voters to come out and caucus, I wouldn’t want to be in Hillary Clinton’s shoes in New Hampshire or South Carolina.

UPDATE Obama’s tact focusing on the more centric independents has some on the left inflamed. Noted liberal blogger Ezra Klein writes

On the down side, some of [Obama's] closing-weeks attacks are a bit, err, worrisome. Going after trial lawyers, for instance? Flooding the radio with ads claiming “Clinton would force people to buy insurance even if they can’t afford it” and “Barack Obama will cover everyone”? The first two statements are simply conservative arguments being uttered by a progressive, the last isn’t true. On some level, this is politics, and all these folks are trying to win, and you’re not going to find any candidates pure as the driven snow and innocent as the newly-born. But Obama’s comfort attacking liberals from the right is unsettling, and if he does win Iowa, it will not be a victory that either supporters or the media ascribe to the more progressive elements of his candidacy. Instead, they will search for the distinctions he’s drawn, and, sadly, a number of those distinctions point away from the heart-quickening progressivism of much of this race, and back towards the old politics of centrist caution and status quo bias.

Such positions lie in drastic contrast to the votes found in Barack Obama’s ultra-liberal Illinois state senate record. Then again, there aren’t all that many “ultra-liberal” independents.