U.S. Rep. Randy Feenstra leads trader consensus at 72% implied probability for the Iowa Republican gubernatorial primary on June 2, driven by his incumbency advantage, strong fundraising, and the April 7 endorsement from former Gov. Terry Branstad, bolstering establishment support amid a crowded field of five candidates. Challenger Adam Steen holds 15.5% thanks to evangelical leader Bob Vander Plaats' February endorsement and early wins like the Scott County GOP caucus straw poll, signaling grassroots appeal. Zach Lahn trails at 10.5% with lesser visibility, while Brad Sherman and Eddie Andrews lag below 2% as vote fragmentation favors Feenstra. Recent Republican registration gains of +350 in March-April reinforce GOP dominance, though county-level forums highlight intra-party tensions.