SurveyUSA (8/31-9/2, likely voters, no trend lines):
Rick Larsen (D-inc): 46
John Koster (R): 50
Undecided: 4
(MoE: ±4%)
This poll comes in the wake of the final top-two primary results giving Koster a 298 vote lead over Larsen. Digging deeper, though, two Democratic candidates took a full 10% of the primary vote, resulting in a final score of 52-48 for Team Blue. This is the second time that Koster has won the top-two primary vote against Larsen, the first time coming in 2000, where Larsen ultimately won the general election by 50-46.
Comparing these results to previous SUSA polls of this district in 2008 and 2006, the partisan composition of the sample isn't what's hurting Larsen; the damage is coming from Larsen's struggles among independent voters. He loses those voters by 12 points, compared to monster-sized wins among indies in the past two cycles. The 18-34 year-old vote has shrunk substantially, too, down to 13% of the sample -- leaving behind a demographic that flocks to Koster by 22 points.
You may take issue with the poll, but this one is shaping up to be a very close race.
