One seeming paradox of the Republican race is that voters who most strongly oppose the war in Iraq have been voting for the candidate, John McCain, who's most strongly identified with supporting it. Lots of commentators find this anamolous. (See Matthew Yglesias.)
But I don't think it's strange at all. McCain attracts Democrats, Independents, and Republicans with weak partisan attachments. Those are the voters least likely to support the war. Mitt Romney, on the other hand, attracts orthodox partisan Republicans, who also happen to support the war.
Now, is it strange that so many people would be voting on the basis of partisanship rather than the war, which is a huge issue? Not really. I think many voters' position on the war -- certainly most Republican voters -- is a function of their partisanship. They support the war because they support George W. Bush. So of course they're voting on the basis of partisan attachment rather than war policy.