McMorris Rodgers, who has represented the large eastern Washington district since 2005, is the chair of the House Republican Conference. She's the fourth highest-ranking Republican in the chamber.
Democrat Joseph Pakootas was leading other contenders for second in Tuesday's primary race to advance to the November ballot. Pakootas is the Colville Tribal council chairman.
The 5th District stretches from Walla Walla in the southeastern portion of the state to the Canadian border.