The Republican presidential nominee has attacked many issues dear to the Arizona senator, including the family of a fallen soldier, NATO and even McCain's own military service.
Eight years after stumping across the nation himself as the Republican Party's presidential candidate, McCain wants to focus on Arizona, yet at nearly every step in recent weeks Trump has dogged him.
McCain slammed Trump last month for saying he might not come to the aid of NATO countries that failed to fulfill their financial obligations.
McCain's primary challengers include tea party activist Kelli Ward, who left the state Senate to take him on, and talk-radio host Clair Van Steenwyk, who in an odd twist is also seeking a U.S. House seat.
The five-term senator is known as a tireless campaigner and has spent the past two weeks crisscrossing the state, appearing in rural Arizona and before veterans groups, the state Chamber of Commerce and others.
At 79, McCain remains a combative politician, jousting with reporters and using his post as chairman of the Senate Armed Services Committee to criticize President Barack Obama's international policies, fight for veterans issues and support Arizona's defense industry and military bases.
The physician from the northwestern community of Lake Havasu City is trying to tap into a widespread dislike of McCain in the conservative wing of the state Republican Party.
