It takes about ten minutes. You have to sort pictures of the candidates into categories. Sometimes you have to sort Obama with positive words like friend and happy, and Huckabee with negative words, and sometimes the other way round (and so on for all combinations of candidates). The idea is that if you sort more quickly if the sort reflects your underlying mental categories. That is, I mentally associate Obama with 'friend' and Huckabee with 'enemy', so sorting that way is quicker for me - I don't have to consciously reflect.
Anyway, the test seems to have worked for me. My results put Obama ahead of the others, next Clinton, and way down at the bottom Huckabee slightly ahead of McCain.
Two aspects of the results surprised me. I thought I was feeling warmer to pics of Clinton than Obama, when I was doing the sorting (because she's a woman), but the results follow my political preference. Conversely I reject Huckabee consciously more than any other candidate, but perhaps unconsciously I am fed up with being ruled by pompous old men, and I think McCain probably hits my 'Oh no not another one' buttons even more strongly than Huckabee does. However, don't get me wrong, they are both way down.