Mark Lamb leads the Arizona 5th Congressional District Republican primary at 56.1% implied probability, reflecting his rapid rise as the consensus frontrunner after entering the race in late October 2025. Polling consistently shows him with 50-69% support against remaining opponent Daniel Keenan, driven by Lamb's prior statewide visibility from the 2024 Senate primary and his background as Pinal County sheriff. Jay Feely and Travis Grantham sit at 6.0% and 3.6% respectively, consistent with reports of their withdrawal or shift to other districts. The July 21 primary date leaves limited time for challengers to close the gap, though recent allegations against Lamb and Keenan's emphasis on local roots and party loyalty represent ongoing variables in a low-turnout contest.