Gallup's LV screen

Gallup's LV screen, results in Romney picking up 6 points in their most recent 7-day tracker and their most recent swing state poll (published by USA Today).

Of registered voters supporting Obama, the LV screen keeps 80% (swing state poll) and 85% (7-day tracker). Of registered voters supporting Romney, the LV screen preserves 90% (swing state) and 96% (7-day tracker). That's quite an assumption. For example, Nate Silver previously estimated that likely voter screens usually result in about a 1.5% gain for Republicans--not a 6 point gain.

FYI, a couple days ago the Obama campaign said:

the problem with Gallup’s outlying data is rooted in their 7 question likely voter screen, which distorts the composition of likely voters

[snip]

Several of the likely voter questions create a bias against groups inclined to support Obama. For example, Gallup asks voters both whether they have voted in their precinct before and where people in their neighborhood go to vote. This creates a bias against registered voters who more likely to move from time to time

There's two things we can do about this. Vote. And GOTV for Obama by going to your local campaign office, participating an event near you, or volunteering from home by making calls.