Seeing as how I lived in MN, I feel fairly qualified to answer. Minnesota has historically been a bastion of blue in a (usually) otherwise red midwest, but this isn't because the state is filled entirely with yellow dog Democrats. read more
There is a strong historical basis for this, and people tend to emulate their parents in these choices. The northern part of Minnesota - the Iron Range - was settled by a large percentage of migrants from Finland. read more
The DFL is strong because of unions in the iron range area as well. People are fairly well educated Minnesota this often leads to liberal leanings. But really it is the rural vs city voting. Minnesota has maybe 5–6 million people and the twin cities metro area houses 2.5–3 million people. read more
In 2004 Bush lost Minnesota by only 4% and Romney lost it by only 7.5% in 2012 and considering he lost the popular vote by 3.9% it would seem that Minnesota would not be out of reach for Republicans. read more