The Iowa caucuses are the first in the Republican primaries calendar. A candidate that does well in Iowa stands to gain significant national media and ‘momentum’ (barring an expectations problem).
Craig Robinson at The Iowa Republican has just ranked the top 10 Republican (possible) candidates as far as their prospects in the Iowa caucuses go. Neither Huckabee nor Palin are on the list (presumably because Robinson doesn’t think that they will run). Absent those two, the top three are:
3. Tim Pawlenty
Based on this, I have increased Bachmann and Gingrich’s percentages in the Republican Standings (right-hand side of blog), from 1% -> 2% and 3% -> 4%, respectively.