So there’s been some question as to how the polls could have been so wrong in NH. Let’s take a look:

1) “Bradley effect.” Dave Weigel described this as a “junk theory” some months ago and gave several examples to disprove this idea. In this particular case, Obama did as well as expected in many polls. He got 36% and was polling between 36 and 40%, except by Zogby who had him at 42%. In other words, Obama didn’t do worse than expected, Hillary did better than expected.

2) Hillary going negative. Hillary dropped two, in my view very disingenuous, negative mailers right before the election. Going negative generally seems to work in politics (see Everything You Think You Know About Politics…and Why You’re Wrong). But it often works by depressing the turn out for your opponents, and as we’ve seen that doesn’t appear to be what happened.

3) Hillary somehow swayed undecided voters. A lot of people are saying her display of emotion wooed women voters, including Obama’s campaign co-chair. I wouldn’t buy that idea alone, but Weigel reports a more nuanced version of this narrative:

“It was the debate,” said a female voice. This male group of pundits looked over and saw Rachel Sklar of the Huffington Post. “The likeability question.” She was talking about the moment in the debate when Charlie Gibson suggested Clinton had a likeability problem, Clinton parried (“That hurts my feelings!”) and Obama leaned into the mic and said “You’re likeable enough.” The camera caught him the second he closed his mouth, looking down, unsmiling, writing notes.

The guys in the room sort of just stood there. I can’t read their minds, but mine was swirling. You know, I’d noticed women at one of the debate-watching parties biting their lips when Obama said that. If Obama had said something like “Well, I like you” or if he’d just kept his mouth shut, Hillary’s Monday tears wouldn’t have had the same impact. “That set up the emotional moment,” Sklar said.

So I’m pretty convinced now: That one-liner swung the primary. If I was a Republican strategist I’d be worried about Clinton for the first time. If she can turn Obama into Rick Lazio (or make him turn himself into Rick Lazio), imagine what she can do to a John McCain or Rudy Giuliani.

ARG says they caught a Hillary upswing due to “the strong swing back among women reacting favorably to Clinton that started after the debate and continued with her comments in Portsmouth” but that it wasn’t reflected in their final polls because they ran out of time.