The big picture from the polls over the last week has been the continuation of Obama’s post-convention bounce and a solidification of Obama’s numbers in a host of key swing states. But there’s one other thing we saw last week that deserves mention: the return of the significant discrepancy in how the race looks in the standard polls now being released by a number of polling organizations and how the race looks in the Gallup and Rasmussen tracking polls.Let’s start with the current PollTracker Average, which gives Barack Obama a 2.6 point margin over Mitt Romney.
Now here’s the PollTracker Average with Gallup and Rasmussen excluded. The number moves pretty dramatically to a 4.5 point margin for Obama.
Beyond the difference in the numbers themselves, you can see the trendline tells its own story. Set aside those two tracking and the post-convention bounce has basically held for Obama. Contrary to pretty much all the other full polls, the tracking polls have reverted back to showing close to a tie race. And that was a difference we’ve seen going back a number of months.
Now, why would this be? It doesn’t seem particularly tied to being a tracking poll since the Reuters/Ipsos tracking poll has held to the pattern of the standard polls since the convention. (Reuters/Ipsos is not included in the PollTracker Average since it’s an online poll.) Rasmussen’s numbers routinely have a Republican tilt. So that’s not a huge mystery. Less clear is Gallup. They don’t have any obviously ideological bias. And they do use cell phones in their surveys. The issue seems to be giving more credence to a 2010 model of the electorate than a 2008 one.
In any case, for now it’s just a pattern to note and recognize. Gallup and Rasmussen have a model of the electorate which looks significantly different from the vast majority of the other pollsters in the field.