The indie label
John McCain and Barack Obama fight for the independent voters of New Hampshire. About 45 percent of the electorate is registered as neither Republican nor Democrat.
Whoever captures the center will have a huge advantage in the national election and will win the "electability" label much sought after by candidates. Until Iowa, Rudolph Giuliani and Hillary Clinton campaigned as if they had the best chance of winning next November. New Hampshire will redefine the field.
Can Obama triangulate? Can McCain shove Romney to the margins?
Also, NH will be a test of whether Obama can keep drawing the young to the polls. The youth vote is terribly unreliable - just ask George McGovern.