David Epso is right that the issues change as soon as the caucuses are over and head to New Hampshire. But I've heard one story too many that talks about how dominant an issue ethanol is in Iowa.
Sure it matters, but one recent report on the general state of the GOP race said not supporting ethanol subsidies was a big reason John McCain was so far down here.
It isn't. McCain has trailed mainly because a whole lot of Republicans just don't like him. For his issue stances, for not being an ideologue, for being too cozy with the media, take your pick. Ethanol is way down the list, and in fact in a recent Iowa debate he volunteered that he was against subsidies even though he wasn't asked about it.
Voters ask about a lot of other issues before they ask about ethanol. Alternative fuels and biofuels in particular are significant, but much of that has to do with wind, R&D spending, and nuclear power.
I'm just sayin', don't oversell the point, mmkay?