When PPP last polled the state in January, around when primary voting kicked off and Romney was not the inevitable nominee, Obama already led Romney by an identical margin as in 2008 (51-41). As supporters of the other Republican candidates have come around to accepting Romney, his position has improved a little elsewhere. But not in Minnesota. Romney now trails by 15 points (54-39).
Just as is the case in the shift against the marriage amendment and toward marriage equality, all the movement for Obama has come with independents. Democrats and Republicans are already polarized, with 94% of Democrats pledging for Obama and 88% of Republicans for Romney. But independents have moved from favoring Obama by nine points in January to 23 now.