Who is actually going to vote in this election and are these the people pollsters are measuring?
While they don't indicate their screen, I believe that some pollsters have a "likely voter" question that's opt in. Whatever they do, their likely voter pool is typically 85-90% of the registered voters. The problem with that is that in 2008 only 71% of registered voters turned out for the election. And that was the highest since 1992. So what they have here is people who say they'll vote, but won't end up voting and a bloated likely voter pool.
If pollsters weigh all their likely voters the same, they are coming up with results that don't reflect the actual electorate. That doesn't mean the polls are wrong but there are people who'll insist 9 ways to Sundays that they'll vote and won't.
I was down at Gary DeLong's campaign office yesterday and discussed "likely" voters. I don't know if this information is available anywhere else but in California you can find out how many times a person has voted in recent elections. They count the last 6 but I'm not sure which ones they count. I know they count 2010, 2008, and 2006 general elections, as well as the 2012 primary. I don't know if 2004 is in there.
Anyone who has voted 4-6 of the last 6 elections is a likely voter. Those who've voted in 0-2 are unlikely voters. Anyone newly registered is a likely voter. I don't know how they handle people who were too young to vote in that many elections and there's nothing indicating whether someone is new to California.
Still, their screen enables them to concentrate on the likely voters. When they poll, they separate the voters into the two groups. While we like to know the overall polling numbers, I don't think that interests them. This enables them to not be concerned with how much weight should unlikely voters should get.
I think this is a great way to separate the two groups. I'd be far less concerned about how the campaign was polling with unlikely voters. Around 90% of likely voters will turn out, but I'd guess only 40-60% of unlikely voters will. It's sort of like walking the slugger to face the weak hitter or double covering the other team's star. You know you can get beat, but you'll take your chances.