[1] After serving in the Arizona State Legislature and U.S. House of Representatives for a number of years, Democrat Ann Kirkpatrick sought to unseat incumbent Republican senator John McCain, who won re-election to his sixth and final term in office.

After hinting in September 2013 that he could retire,[2] McCain subsequently said that the chances he would run again were "pretty good", but his campaign had emphasized that he had not made a decision yet.

Jennifer Duffy of The Cook Political Report noted that McCain did not fit the profile of a "complacent, long-serving incumbent", saying: "It's not an easy thing to take him on.

"[9] In September 2014, McCain began having "serious conversations" with state Republicans, local officials and key supporters about running for re-election.

[5] A survey by Public Policy Polling in March 2014 found that McCain was the most unpopular Senator in the country, with 30% of Arizonans approving of him to 54% who disapproved.

[10] An April 2014 survey by The Polling Company for Citizens United Political Victory Fund found that 64.2% of Republican primary voters favored "a new person" to 29.3% who thought that "Senator McCain deserves to be re-elected to another six-year term."

By early 2014, McCain's apostasies were enough that the Arizona Republican Party formally censured him for having what they saw as a liberal record that had been "disastrous and harmful".

[6] However, McCain still had a large warchest – $1.7 million as of June 2014 – and would be helped by Arizona state law, which allows independents to vote in the Republican primary.

"[6] In late October, it was revealed that McCain had scheduled a meeting with supporters two days after the 2014 midterm elections to "discuss my thoughts on my own re-election in 2016.

[14][15] The Super PAC "Arizona Grassroots Action" was created, which raised almost $300,000 and supported McCain-allied candidates with mailers and automated phone calls, bringing attention to what were previously low-profile and uncontested races.

[14][16] Schwartz attacked McCain for using his "prominence and money and influence" to "ramrod" his critics and former Maricopa County Republican Party Chairman A.J.

"[20] Towards the end of February, Salmon and Schweikert began to distance themselves from the race,[21][22] with State Senator Kelli Ward revealing that she was considering a run.