The latest from Public Policy Polling:

The Republican caucus in Iowa is headed for a photo finish, with the three leading contenders all within two points of each other. Ron Paul is at 20%, Mitt Romney at 19%, and Rick Santorum at 18%. Rounding out the field are Newt Gingrich at 14%, Rick Perry at 10%, Michele Bachmann at 8%, Jon Huntsman at 4%, and Buddy Roemer at 2%.
The momentum in the race is completely on Santorum’s side. He’s moved up 8 points since a PPP poll earlier in the week, while no one else has seen more than a one point gain in their support. Among voters who say they decided who to vote for in the last seven days he leads Romney 29-17 with Paul and Gingrich both at 13.