“Does any of that seem at all plausible?”
You do realize you’re talking about a very liberal state whereas the Fox poll is about the nation as a whole? Based upon the margin that Obama won Deleware it is tied for the sixth most liberal state in the U.S.
As such: “Republicans 32%, Democrats 45%, Independents 21%” seems quite plausible to me. In fact by the estimate of FiveThirtyEight.com, there are 15 senate seats held by the Democrats that are more likely to go Republican than Deleware. Admittedly this isn’t just because the Democrats are dominating in the polls, but also because there are so many polls that the leads they show become more statistically significant.
I do think Delaware is relatively liberal.
I actually think Massachussetts is more liberal.
I do not think the Dems have a 13% participation advantage. I think the Dems are far less mobilized than 2008.
I think the Republicans are far more mobilized than 2008.
All of these things point to outcomes different than the assumptions of this poll.