Pinal County Sheriff Paul Babeu has outpaced four challengers to win the Republican nomination in the sprawling 1st Congressional District, which includes much of Arizona outside the Tucson and Phoenix metro areas.
Babeu's victory earns him the right to try to wrest the district from Democratic control.
Incumbent Ann Kirkpatrick is vacating the seat to run for U.S. Senate, and Democrat Tom O'Halleran easily won the Democratic primary Tuesday.
Six Republicans appeared on the primary ballot, although Arizona House Speaker David Gowan suspended his campaign and threw his support behind Springerville rancher and businessman Gary Kiehne.
The others in the race were former Secretary of State Ken Bennett, retired Air Force pilot Wendy Rogers and businessman Shawn Redd.