Mark Lamb holds a commanding lead in Arizona’s 5th Congressional District Republican primary due to his statewide name recognition from a prior U.S. Senate bid, seven years as Pinal County sheriff, and endorsement from President Trump in the open-seat contest to succeed Representative Andy Biggs. These factors have allowed Lamb to build early donor networks and broad party support ahead of the July 21 primary. The remaining candidates, including state legislator Travis Grantham and former NFL kicker Jay Feely, have not mounted comparable fundraising or organizational efforts. While the July vote is still weeks away, the market consensus reflects the structural advantages of incumbency-like visibility and high-profile backing in a solidly Republican district. Late developments such as unexpected scandals, health issues, or shifts in national messaging could still alter the trajectory before ballots are cast.