What the Iowa entrance polls will tell us tonight – and what they won’t

We’re just a few hours away from the first entrance polls of the 2012 race. The release will probably tell us quite a bit about how the campaign is playing out so far with primary season voters who’ve had the most exposure to the candidates. But first, it’s important to take a look at what they won’t.

Entrance polls are a bit different than exit polls; they take the pulse of voters just before, not after they head in to vote. They might not tell us who the winner will be, especially not in the early going. But they’re still worth watching. Here’s why:

Think of them as a giant focus group: They can give us a partial snapshot of who showed up today in one small part of the country, and what drove their vote. They can show which candidate had the most momentum, by letting us know who late deciders broke for, and some of the factors that may have driven their decision. They can give us our first real clue as to the candidates’ relative strength (or weakness) with key GOP voting blocs like evangelicals and tea party supporters; important demographic blocs like women and seniors; and highly-prized independent voters. And they can give us an initial glimpse of how enthusiastic a candidate’s supporters are – a key ingredient in any successful general election campaign.

Later tonight, we’ll get the final vote tally out of Iowa. The entrance polls will give us our first hint as to how and why we got there.

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