Republican Martha McSally easily defeated primary challengers Tuesday and advances to take on incumbent Democrat Ron Barber for the second time.
She won 70 percent of the votes reported by 9:15 p.m. Shelley Kais received 8 percent votes and Chuck Wooten had 22 percent.
The district includes part of Pima County and all of Cochise County.
McSally is looking for a rematch with incumbent Democrat Ron Barber, who was unopposed in the primary election. Barber's 2012 victory was won by 2,454 votes.
In a speech to supporters Tuesday night, McSally said she now has 70 days to convince Southern Arizona that a change is needed in Washington.
Barber is considered to be one of the House's most vulnerable Democrats, in part because of his narrow victory over McSally in 2012.
In a speech to his supporters, Barber said McSally "doesn’t understand our community," but he expects a tight race with dark money pouring in by the millions.
Kais was refusing to concede until every vote was counted when she left an election night party at 9:20 p.m.