Mark Blumenthal and Charles Franklin note here that Mike Huckabee may soon overtake Rudy Giuliani in Iowa polling. Giuliani is trending downward, while Huckabee is on the rise. Looking at Blumenthal and Franklin's data, it becomes clear that the Iowa GOP caucus currently is a two-tier race, with Mitt Romney alone in the first tier and Fred Thompson, Giuliani, and Huckabee together in the second. Since it is likely that there will be three tickets out of Iowa, one of those second-tier candidates will be left out. Which suggests that the second-tier will be where a lot of the exciting Iowa jousting takes place. As always, one should note that four years ago today Howard Dean and Richard Gephardt were battling for the top-spot in Iowa. John Kerry, who won Iowa in the end, was in third-place.