I suppose a shockingly close result isn't out of the question (Oberstar is getting on and that's not a good thing when a big swing is on) but I have trouble seeing this, especially with Dayton leading in the polls (however narrowly). I mean, obviously, if it is anywhere near this close or if (heaven forbid) Oberstar actually loses then we're dealing with a landslide and - probably - a near total Democratic collapse in the Mid West.
Obama did very well in the Midwest, surprisingly well, in fact.
Which is why the trend against the Democrats is strongest here.