Rasmussen Reports: For the fifth straight survey, the GOP field has a new frontrunner in Iowa. The latest Rasmussen Reports national telephone survey of Likely Iowa Republican Caucus Participants shows former Massachusetts Governor Mitt Romney with 23% of the vote, only slightly ahead of former House Speaker Newt Gingrich who has 20%. Texas Congressman Ron Paul is right behind with 18% of the vote. Texas Governor Rick Perry earns 10% support, with no other candidate grabbing double-digits.