Barack Obama holds a 49-46 lead over John McCain in Minnesota, according to a new poll conducted by SurveyUSA. That’s within the survey’s 3.9 percent margin of error. No other poll released in recent weeks has shown the presidential contest to be that tight in Minnesota. In fact 7 of the last 10 surveys in the state have shown the Democrat with a double-digit lead.

Poll guru Nate Silver, of The Plank and FiveThirtyEight renown, discounts the SurveyUSA poll as an outlier:

–> Don’t worry too much about that SurveyUSA result in Minnesota, which shows Obama just 3 points ahead. SurveyUSA’s polling in Minnesota has been very, very weird all year; they’ve never shown Obama with larger than a 6 point lead in their likely voter model, and had McCain ahead in the state as recently as October 1st. SurveyUSA does not have a Republican lean in general, but in Minnesota, it has consistently had a huge one.

There’s little doubt, regardless of who’s conducting the poll, that Minnesota’s U.S. Senate race is extremely tight. Polls have been bouncing back and forth in recent days between razor-thin leads for either Sen. Norm Coleman or Democrat Al Franken. The SurveyUSA study, commissioned by KSTP-TV (Channel 5), shows the incumbent with a 44-39 lead, just outside the margin of error. Independence Party candidate Dean Barkley trails with 16 percent of the vote.