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,Democrat Kyrsten Sinema Wins Arizona Senate Seat. NPR. 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.

Background 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.

Republican primary Candidates On the ballot

Joe Arpaio, former Maricopa County sheriff Nicholas N. Glenn (write-in candidate) William Gonzales (write-in candidate) Martha McSally, U.S. representative from and retired U.S. Air Force ColonelArizona Rep. McSally tells colleagues she’ll run for Senate , The Washington Post, Bob Christie (AP), November 7, 2017. Retrieved November 7, 2017. Kelli Ward, former state senator and candidate for the U.S. Senate in 2016

Failed to file 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

Withdrew Jeff Flake, incumbent U.S. senator

Declined Andy Biggs, U.S. representative from (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 (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 (ran for re-election) John Shadegg, former U.S. representative

Endorsements

Polling Poll source Date(s)administered Samplesize Marginof error JoeArpaio MarthaMcSally KelliWard Other UndecidedData OrbitalData Orbital August 21–22, 2018 600 ± 4.0% 18% 48% 22% 1% 8%OH Predictive InsightsOH Predictive Insights August 14–15, 2018 578 ± 4.1% 13% 47% 27% – 12%OH Predictive InsightsOH Predictive Insights July 23–25, 2018 576 ± 4.1% 15% 35% 27% – 23%Gravis MarketingGravis Marketing June 27 – July 2, 2018 501 ± 4.4% 24% 36% 27% – 14%Emerson CollegeEmerson College June 21–22, 2018 305 ± 5.9% 18% 32% 19% 7%Christian Diegel with 3%, Craig Brittain and Michelle Griffin with 2%, Nicholas Tutora with 0% 23%Data OrbitalData Orbital June 19–21, 2018 550 ± 4.2% 17% 38% 23% 2% 21%Marist CollegeMarist College June 17–21, 2018 371 ± 6.7% 21% 30% 28% <1% 21%OH Predictive InsightsOH Predictive Insights June 11–12, 2018 600 ± 4.0% 14% 39% 25% – 22%Remington (R)Remington (R) May 23–24, 2018 2,011 ± 2.3% 25% 42% 23% – 10%Magellan Strategies (R)Magellan Strategies (R) April 11–12 and 15, 2018 755 ± 3.6% 26% 36% 25% 6% 7%OH Predictive InsightsOH Predictive Insights April 10–11, 2018 302 ± 5.6% 22% 27% 36% – 15%Data OrbitalData Orbital January 11–15, 2018 500 ± 4.4% 22% 31% 19% – 27%OH Predictive InsightsOH Predictive Insights January 9, 2018 504 ± 4.4% 29% 31% 25% – 15%WPA Intelligence (R)WPA Intelligence (R) November 15–16, 2017 500 ± 4.4% – 38% 36% – 26%OH Predictive InsightsOH Predictive Insights November 9, 2017 323 ± 5.5% – 34% 42% – 24%Revily (R)Revily (R) October 28–31, 2017 380 ± 3.0% – 21% 32% 15%Matt Salmon 9%, Craig Brittain 4%, Nicholas Tutora 2% 34%

with Jay Heiler Poll source Date(s)administered Samplesize Marginof error JayHeiler MarthaMcSally MattSalmon DavidSchweikert JohnShadegg KelliWard UndecidedData OrbitalData Orbital October 26–28, 2017 500 ± 4.4% 1% 19% 10% 5% 4% 26% 28%

with Jeff Flake Poll source Date(s)administered Samplesize Marginof error JeffFlake JeffDeWit NicholasTutora KelliWard Other UndecidedGBA StrategiesGBA Strategies August 30 – September 7, 2017 500 ± 4.4% 31% – – 58% – 11%JMC Analytics (R)JMC Analytics (R) August 26–27, 2017 500 ± 4.4% 21% – 3% 47% – 29%HighGround Public AffairsHighGround Public Affairs August 18–19, 2017 273 ± 5.9% 28% – – 43% 5% 24%Political Marketing International (R-Ward)Political Marketing International (R-Ward) February 7, 2017 921 ± 5.0% 23% – – 30% – 47%Remington Research GroupRemington Research Group November 15–16, 2016 1,122 ± 2.9% 30% 38% – 15% – 17% 33% 42% – – – 25% 35% 35% – – – 30%

Results

Democratic primary Candidates On the ballot

Deedra Abboud, attorney Kyrsten Sinema, U.S. representative from

Failed to file 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

Withdrew Jim Moss, businessman, activist and former teacher

Declined 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)

Endorsements

Polling Poll source Date(s)administered Samplesize Marginof error DeedraAbboud KyrstenSinema Other UndecidedData OrbitalData Orbital June 25–27, 2018 550 ± 4.2% 7% 63% 2% 29%Emerson CollegeEmerson College June 21–22, 2018 260 ± 6.2% 8% 51% 12%Richard Sherzan with 4%, Cheryl Fowler and David Ruben with 3%, Bob Bishop with 2% 30%

Results

Libertarian primary Candidates

Declared

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

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

Green primary Candidates

Declared

Angela Green (write-in candidate)

Removed Eve Reyes-Aguirre, activist

Results

General election

Debates

Complete video of debate, October 15, 2018

Predictions SourceRankingAs ofThe Cook Political Report October 26, 2018Inside ElectionsNovember 1, 2018Sabato's Crystal BallNovember 5, 2018CNNOctober 30, 2018RealClearPoliticsNovember 5, 2018FiveThirtyEightNovember 6, 2018Daily KosOctober 26, 2018Fox NewsOctober 30, 2018

Endorsements

Fundraising Campaign finance reports as of October 17, 2018Candidate (party)Total receiptsTotal disbursementsCash on handKyrsten Sinema (D)$19,287,249$20,249,341$1,301,542Martha McSally (R)$16,211,836$13,688,178$2,523,657Source: Federal Election Commission

Polling