Why does this keep coming up?
There is NO oversampling. There is no undersampling. There is only random sampling. The people self identify as whatever party affiliation they choose when they are RANDOMLY sampled. That many Democrats were in the RANDOM sample. That many GOP and that many Independents.
Oregon’s Dem/GOP/Ind mixture may be exactly what these samples said. Kerry won it by 4% in 2004. Party affiliation moved away from the GOP since then, despite recent gains.
Forget Oregon.