Polls close in four states, including the last of the battlegrounds, Iowa (six) and Nevada (six).
Iowa's been leaning toward Obama, but watch how the vote breaks down geographically. Can Romney's advantage in GOP-heavy western Iowa overcome Obama's edge in eastern swing territory?
If Obama wins Ohio and Wisconsin, Romney would have to have help from the West, in places like Nevada and Colorado. Nevada, where two-thirds of the electorate votes early, has been moving Obama's direction in recent weeks, powered by strength in huge labor and Hispanic voting blocs. A Romney incursion there would really mean something.
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