In all the hothouse discussion of polls, there’s one point you hear again and again from Romney supporters: Romney can’t be winning independents so consistently and also be behind. But that’s not really true.

...One point to keep in mind here is that we keep this data set of ‘adults’ rather than registered or likely voters. That makes it somewhat different from the voting electorate. But it also removes swells of voter and partisan enthusiasm from the trend. These are polls which simply ask people over 18, how do you identify in partisan terms. So we get a good apples to apples comparison over time.

A few things jump right out. The big thing is that independent identification skyrocketed and GOP identification plummeted in the Fall of 2010 — notably, this started just in advance of the 2010 midterm election.

Now, unless you assume that the US has moved strongly to the left since 2010, it seems pretty clear that what happened was an exodus from the GOP to the right. In other words, a lot of people left the Republican party, in identification terms. But they didn’t become Democrats. And it doesn’t seem (at least from the politics of the last two years) like they became more moderate of ‘centrist’ in ideological terms. They simply reidentified themselves as independents. One more thing I’d add and this is part is just my supposition. But I think in a lot of cases they actually re-identified because the GOP wasn’t right-wing enough, call it a Tea Party exodus from the GOP...

http://talkingpointsmemo.com/archives/2012/10/can_romney_win_indies_lose.php?ref=fpblg