Se espera una noche larga en Michigan

Nate Silver:

People sometimes apply the term “tossup” a bit too broadly, using it to refer to anything close enough that they don’t want to render a prediction about it.

In Michigan, however, the term is appropriate. Rick Santorum, who once trailed Mitt Romney badly in the state, then surged to a clear lead there, then saw Mr. Romney regain his footing and pull back ahead, appears to have some late momentum in the race — perhaps just enough to win, and perhaps not.

(...) One word of warning: factors like early voting, crossover voting and the relatively large amount of demographic diversity within Michigan will make it tricky to call the state based on exit poll results and the first few precincts that report. For instance, if early and absentee results are reported before those cast on Election Day, as is common in some states, Mr. Romney could initially emerge with a lead that proves ephemeral. I generally take the view that the news networks are too quick to call a race — shouldn’t have we learned something from Florida in 2000 or Iowa this year? — but there is reason to be especially cautious here.