Mitt Romney was able to get 31% and win comfortably over his next closest competitors: Mike Huckabee and Sam Brownback.
As USAElectionPolls.com points out, 31% is already roughly the same percentage Romney polls in Iowa state polls with Rudy Giuliani, Fred Thompson, John McCain, and Newt Gingrich included. There is also a sizeable Undecided group, about 15%.
By removing Giuliani, Thompson, McCain, Gingrich, and the undecideds from the polls, Romney would be dominating his next closest competitor by about 800%, USAElectionPolls.com concludes. They admit that the flaw in doing this is assuming the Giuliani, Thompson, McCain, and Gingrich voters would be evenly distributed over the rest of the field in the exact same proportions. The second flaw is assuming the undecideds will distribute themselves in the same proportion as the decideds. The third flaw is that by removing votes in a poll, a much larger margin of error as much as 9% is injected into the poll.
Despite these flaws, Romney is still projected to make roughly 70% in 3 of the 4 latest Iowa polls. For him to get 31% at the Ames Straw Poll suggests that either Romney voters stayed at home assuming an easy win or that Mike Huckabee and Sam Brownback are closing the gap.
Go to 2008 Ames Straw Poll Research.