Twitter is reporting that IBD/TIPP hard-weights to 2008 party identification and turnout, so Romney will never lead there. I haven’t found confirmation of that, but I haven’t looked either.
If you apply party identification from Gallup. Romney is up by about a point in that poll
http://pollmashing.com/poll/8/B1C7359A-EB91-D2A3-A513-D44EDDB1B4F3#.UIhPb2l24iU