The best way to think about a poll, outside issues of sampling or methodology, is as a snapshot in time. A well-crafted poll can give you a sense of the state of the race--at the time the poll is taken. The impact of major campaign events can be missed if the poll was conducted before they happened, even if the results were reported during the event. Rasmussen and Gallup poll daily using moving averages, enabling them to capture changes in the daily horse-race of the campaign. Today's data from Gallup confirms that the "cancer" ad attacking Romney has strongly backfired on Obama. 

Gallup's latest results, polled between Tuesday and Thursday, days dominated by the controversy over the "cancer" ad show Obama's approval ratings moving down 3 points and his disapproval rating moving up 3. 51% of voters now disapprove of Obama and only 43% approve. Romney's support edged up 1. Gallup shows the race tied at 46%. 

A six-point swing in approval ratings is pretty significant in a moving average. Rasmussen also showed Romney gaining strength mid-week, moving into a 4 point lead over Obama. This is significant, because they are the only two pollsters who were polling throughout the controversy. 

Three other polls were released this week, all showing leads for Obama. The first, Reuters, was conducted last Wednesday through Sunday, missing the entire controversy. The Fox poll was conducted Saturday through Monday, also missing it. CNN was conducted Tuesday and Wednesday, just as the controversy was unfolding. (Side note: always beware polls conducted significantly over a weekend--very erratic sampling.) 

The Obama campaign is basing most of its reelection on smearing Romney. Today's Gallup results, which show significant weakening of Obama during the controversy, should light a path for Romney. Fight back. The voters are watching. 

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