2018 United States Senate election in Arizona

The 2018 United States Senate election in Arizona took place on November 6, 2018. Incumbent Republican Senator Jeff Flake did not seek a second term. The election was held concurrently with a gubernatorial election, other elections to the U.S. Senate, elections to the U.S. House of Representatives, and various other state and local elections.

Primaries were held on August 28, 2018, three days after the death of longtime U.S. Senator John McCain. Martha McSally won the Republican nomination, while Kyrsten Sinema won the Democratic nomination. Green Party candidate Angela Green was also on the ballot, but ended her campaign and endorsed Sinema before Election Day.

The Associated Press called the race for Sinema on November 12, 2018, and McSally conceded that day. Sinema became the first Democrat to win a U.S. Senate seat in Arizona since 1988. McSally was subsequently appointed by Governor Doug Ducey to the other vacant Senate seat in Arizona, left open after McCain's death and then held on an interim basis by Jon Kyl.

Arizona, located along the United States border with Mexico, has a unique political history. Upon its admission to the Union in 1912, the state was dominated by Democrats who had migrated there from the South, and aside from the landslide victories of Republicans Warren G. Harding, Calvin Coolidge, and Herbert Hoover, the state voted for Democrats until 1952, when Dwight Eisenhower carried it, and began a lengthy streak of Republican victories interrupted only by Bill Clinton's narrow victory in 1996. Since then, the state had remained Republican, and was won by Donald Trump with a 3.5% margin in 2016, although Trump's margin of victory was much smaller than that of past Republican presidential nominees.

Incumbent Republican Senator Jeff Flake announced in October 2017 that he would retire at the end of his current term instead of seeking reelection for another term in 2018. Flake had previously indicated his intent to run for reelection in March 2017. However, he was considered vulnerable due to persistently low approval ratings, a poor relationship with President Trump, and the threat of a primary challenge from former state senator Kelli Ward, who promised to run on a more pro-Trump platform. Additionally, he had won his first term in 2012 by only 3 percentage points, even though Republican presidential nominee Mitt Romney won Arizona by 9.

U.S. Representative Martha McSally at the launch of her senatorial bid in January 2018

Former State Senator Kelli Ward at a campaign event prior to the Republican primary in August 2018

• Joe Arpaio, former Maricopa County sheriff

• Nicholas N. Glenn (write-in candidate)

• William Gonzales (write-in candidate)

• Martha McSally, U.S. representative from Arizona's 2nd congressional district and retired U.S. Air Force Colonel

• Kelli Ward, former state senator and candidate for the U.S. Senate in 2016

• Craig Brittain, owner and co-founder of the revenge porn website IsAnybodyDown?

• Christian "C.J." Diegel, financial advisor

• Michelle Griffin

• Shawn Redd

• Nicholas Tutora, pharmacist

• Jeff Flake, incumbent U.S. senator

• Andy Biggs, U.S. representative from Arizona's 5th congressional district (ran for re-election)

• Jan Brewer, former governor of Arizona

• Mark Brnovich, attorney general of Arizona (ran for re-election)

• Jeff DeWit, treasurer of Arizona (nominated as NASA chief financial officer)

• Trent Franks, former U.S. representative

• Paul Gosar, U.S. representative from Arizona's 4th congressional district (ran for re-election)

• Robert Graham, former chair of the Arizona Republican Party

• Christine Jones, former GoDaddy executive, candidate for governor in 2014 and candidate for AZ-05 in 2016

• Bill Montgomery, Maricopa County Attorney

• Ben Quayle, former U.S. representative and son of former Vice President Dan Quayle

• Matt Salmon, former U.S. representative and nominee for governor in 2002

• David Schweikert, U.S. representative from Arizona's 6th congressional district (ran for re-election)

• John Shadegg, former U.S. representative

Results by county: .mw-parser-output .legend{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .legend-color{display:inline-block;min-width:1.25em;height:1.25em;line-height:1.25;margin:1px 0;text-align:center;border:1px solid black;background-color:transparent;color:black}.mw-parser-output .legend-text{}  McSally   30–40%   40–50%   50–60%   60–70%   Arpaio   30–40%

U.S. Representative Kyrsten Sinema at a campaign event in October 2018

Attorney Deedra Abboud at a campaign event in April 2017

• Deedra Abboud, attorney

• Kyrsten Sinema, U.S. representative from Arizona's 9th congressional district

• Bob Bishop, pilot

• Matt Jette

• David Ruben, physician

• Chris Russell, attorney

• Richard Sherzan, retired administrative law judge, former Iowa state representative and candidate for the U.S. Senate in 2016

• Jim Moss, businessman, activist and former teacher

• Randall Friese, state representative

• Mark Kelly, astronaut, scientist, U.S. Navy captain and husband of former U.S. representative Gabby Giffords (later elected to Arizona's Class 3 Senate seat in 2020)

• Ann Kirkpatrick, former U.S. representative and nominee for the U.S. Senate in 2016 (ran for U.S. House)

• Greg Stanton, Mayor of Phoenix (ran for U.S. House)

Results by county:   Sinema   60–70%   70–80%   80–90%

• Adam Kokesh (write-in candidate), anti-war activist and U.S. presidential candidate in 2020

• Doug Marks, veteran and write-in candidate for IL-14 in 2010

• Angela Green (write-in candidate)

• Eve Reyes-Aguirre, activist

Results by county:   Green   90–100% No votes

Sinema and McSally in a 2018 senatorial debate

• Complete video of debate, October 15, 2018

Sinema won five of nine congressional districts.

The race was too close to call on election day. On November 7, 2018 (one day after the election), KGUN 9 reported that McSally held a narrow lead of 0.9%, with thousands of ballots still uncounted. On November 8, Politico reported that Sinema had taken a 9,610-vote lead. Due to the closeness of the vote count, the Associated Press and other major news outlets did not call the race for Sinema until November 12, 2018, six days after the election. McSally conceded the race to Sinema that day. The results were certified on December 3, 2018.

This was the first Senate election in Arizona won by a Democrat since 1988. Sinema is the first woman to be elected to the U.S. Senate from Arizona. Sinema would later leave the Democratic Party to become an independent in December 2022, although she would continue to caucus with them in the Senate until the end of her term.

On December 18, 2018, Governor Doug Ducey appointed McSally to fill Arizona's other Senate seat. The seat was left vacant after the resignation of Jon Kyl, who himself had been appointed following the August 25, 2018 death of John McCain. Both Sinema and McSally were sworn in with the 116th United States Congress on January 3, 2019, marking the first time in history that Arizona was represented by two women in the United States Senate and making Arizona the second state to be represented by two women from different parties. Ducey stipulated that Sinema would be sworn in first, making her the senior senator; this way, he said, the decision of Arizona's voters would be respected.

Under Arizona law, McSally's appointment was only valid for the duration of the 116th Congress, and a special election for her seat was held in November 2020 to determine who would finish the remainder of McCain's unexpired term (which expired in 2023). McSally was defeated by Democrat Mark Kelly in that special election.

Partisan clients

• "Arizona Senate Election Results: Martha McSally vs. Kyrsten Sinema". The New York Times. January 28, 2019. (constantly updated)
• Candidates at Vote Smart
• Candidates at Ballotpedia
• Campaign finance at FEC
• Campaign finance at OpenSecrets

Official campaign websites

• Kyrsten Sinema (D) for Senate
• Martha McSally (R) for Senate Archived August 26, 2018, at the Wayback Machine
• Adam Kokesh (L) for Senate Archived July 12, 2018, at the Wayback Machine
• Angela Green (G) for Senate