From political prognosticator Nate Silver at The New York Times.

The FiveThirtyEight forecast model now projects a win for Mr. Romney by about four points in Michigan, roughly bisecting the Rasmussen Reports and Mitchell Research polls. Although that is inherently a fairly small margin, it is more meaningful given that there are just four full days of campaigning until Michigan votes; the model makes Mr. Romney about a 2:1 favorite in the state.