Obama's performance compared to polls in '08 swing states (most underestimated his margins).
Though the polls pointed to an Obama victory in 2008, many of the polls underestimated Obama's margins ... some significantly. In fact, in all but two swing states, Iowa and New Hampshire, Obama out-performed the average of polls:
In some states, the margins were pretty large ... specifically in New Mexico and Nevada. Yes, some of those differences don't look huge. But think about this: The polls in Virginia are essentially tied. An additional 1.9 points solidifies it in Obama's corner. In Ohio, where his average is 2.1, an additional 1.5 gives him a 3.6 point victory. That's near the level he saw in '08.
Basically, what this suggests is that most swing states underestimated Obama's support ... or at least undercounted it in the polls. On its face, the margins weren't dramatic. But in a close race, it could dramatically shift the race in his favor.
If Obama out-polls the polls similar this go around, he will win Ohio, Virginia, Colorado, Nevada, New Mexico and potentially Florida.
That's why ground game and turnout is so important. But even four years ago, it seemed the media was underestimating Obama's GOTV effort, as he averaged nearly two-points better in swing states than the polls suggested.