PPP's latest:
Newt Gingrich's campaign is rapidly imploding, and Ron Paul has now taken the lead in Iowa. He's at 23% to 20% for Mitt Romney, 14% for Gingrich, 10% each for Rick Santorum, Michele Bachmann, and Rick Perry, 4% for Jon Huntsman, and 2% for Gary Johnson.
Nate Silver includes the poll in his voting model:
The model gives him a 44 percent chance of winning Iowa based on the current standing of the candidates and the historic uncertainty of polling-based forecasts. Mr. Romney has a 32 percent chance of winning, while Mr. Gingrich’s chances have crashed to 15 percent.
Josh Marshall's takeaway:
Attack ads work; especially when they’re unrebutted. And even more so against a deeply flawed candidate.
Chart from Charles Franklin.
The Dish 