Polls in Nevada are notoriously bad. People thought McCain could win Nevada in 2008, and that Obama would surely do better in Colorado, Virginia, and Pennsylvania than Nevada. We saw how that turned out. People thought Reid was going to lose in 2010, since he was consistently polling a few points behind Angle. He won by 5.5. People also thought Nevada was an ultratight swing state in 2012, and it turned out to be... not that close. Obama won it by more than every other swing state except Wisconsin. While Dean Heller did manage to hold on in 2012 (thanks to a flawed opponent), he won by much less than the polls suggested. People often counter this example with 2014, but Democrats didn't lift a finger to contest the gubernatorial race in Nevada that year, and Sandoval is extremely popular, even among the Latinos, the group that pollsters struggle with in Nevada (so if they were missing Latino voters, it didn't result in the same Republican bias it has in other years.) I stand by my prediction that Hillary will comfortably win Nevada, and everyone will be shocked AGAIN that Nevada didn't end up being close, even though the polls showed it to be.
As for Iowa, a few things could be at play here. Iowa
could be trending Republican, given how poorly Democrats did in 2014. It could also be that Trump is benefiting from the fact that there are very few minorities in Iowa, and this might be the year that Iowa's demographics catch up to it a bit. (We're not seeing that in New England or the PNW, since whites in those regions vote different from whites in the Midwest.) It could also be that Hillary will do fine in Iowa as well, since Iowa is a state where ground game is crucial. That's one of the big reasons why Obama always did so well in Iowa, and was perhaps a reason why Cruz managed to upset Trump there in the caucus. Perhaps, in some of these smaller states where organization really makes a huge difference, polls are understating Hillary's advantage. Or, it could be a combination of the three.
If Hillary wins by 6 or 7 points nationally, she'll almost certainly win Iowa (though maybe not by a lot), and she'll cruise by in Nevada.
