The 2020 United States Senate special election in Arizona was held on November 3, 2020, following the death in office of incumbent Republican U.S. Senator John McCain on August 25, 2018. Governor Doug Ducey was required by Arizona law to appoint a Republican to fill the vacant seat until a special election winner could be sworn in. On September 5, 2018, Ducey appointed former U.S. Senator Jon Kyl to fill McCain's seat. However, Kyl announced he would resign on December 31, 2018.
On December 18, 2018, Ducey announced that outgoing U.S. Representative Martha McSally would be appointed to fill the seat following Kyl's resignation. McSally was sworn in as the state's junior U.S. Senator on January 3, 2019, less than two months after she was defeated by Democrat Kyrsten Sinema for Arizona's Class 1 U.S. Senate seat. McSally ran to complete the term, defeating skincare executive Daniel McCarthy in the Republican primary. She faced former astronaut Mark Kelly, who ran uncontested in the Democratic primary. Primary elections took place on August 4, 2020.
Once a reliably Republican state, Arizona trended more purple in the late 2010s. Kelly significantly outraised McSally and led by about 5% in the average poll leading up to Election Day.
Kelly defeated McSally by a margin of 2.4% on election night, thereby flipping the seat Democratic. As a result, he outperformed Joe Biden in the concurrent presidential election, who defeated President Donald Trump by a margin of 0.3% in the state, but underperformed his polling average. Kelly became the first Democrat to win the Class 3 Senate seat since Carl Hayden won his last term in 1962.
Kelly was sworn in on December 2, 2020, marking the first time since 1953 that Democrats held both of Arizona’s Senate seats.
Interim appointments Appointees Jon Kyl, former U.S. senator, former U.S. Representative for Arizona's 4th congressional district and former Senate Minority Whip, resigned December 31, 2018 Martha McSally, former U.S. representative for Arizona's 2nd congressional district, 2018 Republican nominee for U.S. Senate, assumed office January 3, 2019
Potential candidates not appointed Kirk Adams, incumbent chief of staff to incumbent governor of Arizona Doug Ducey and former speaker of the Arizona House of Representatives Barbara Barrett, Secretary of the Air Force and former United States Ambassador to Finland Jan Brewer, former governor of Arizona and former secretary of state of Arizona Paul Gosar, incumbent U.S. representative for Arizona's 4th congressional district Eileen Klein, former treasurer of Arizona and former chief of staff to former governor of Arizona Jan Brewer Cindy McCain, widow of former U.S. senator John McCain Meghan McCain, daughter of former U.S. senator John McCain Mick McGuire, incumbent adjutant general of the Arizona National Guard Karrin Taylor Robson, businesswoman and incumbent member of the Arizona Board of Regents Matt Salmon, former U.S. representative, 2002 gubernatorial nominee and former chairperson of the Arizona Republican Party David Schweikert, incumbent U.S. representative for Arizona's 6th congressional district John Shadegg, former U.S. representative for Arizona's 3rd congressional district Kelli Ward, former candidate for U.S. Senate in 2016 and 2018 Grant Woods, former Republican Arizona Attorney General and former congressional chief of staff to former U.S. senator John McCain
Republican primary Incumbent McSally faced one challenger: Daniel McCarthy, a skincare company executive. McCarthy's independent wealth was expected to set up a bruising and expensive primary campaign; however, McSally won the primary in a landslide.
Candidates Nominee Martha McSally, incumbent U.S. senator and former U.S. Representative for Arizona's 2nd congressional district
Eliminated in primary Sean Lyons (as a write-in candidate) Daniel McCarthy, skincare company executive
Withdrawn Craig Brittain, former revenge porn site operator PT Burton Mark Cavener Floyd Getchell Ann Griffin, former teacher Josue Larose, 2016 Republican presidential candidate and 2012 Republican candidate for Louisiana's 2nd congressional district
Declined Kirk Adams, incumbent chief of staff to incumbent governor of Arizona Doug Ducey and former Speaker of the Arizona House of Representatives Joe Arpaio, former Sheriff of Maricopa County and candidate for U.S. Senate in 2018 (ran for Maricopa County Sheriff) Doug Ducey, governor of Arizona Paul Gosar, U.S. representative for (ran for re-election) Jon Kyl, former two-time U.S. senator, former U.S. Representative for , and former Senate Minority Whip Blake Masters, president of the Thiel Foundation Curt Schilling, former Major League Baseball player and Blaze Media commentator Fife Symington, former governor of Arizona
Endorsements
Primary results
Democratic primary Candidates Nominee Mark Kelly, retired astronaut, engineer, retired U.S. Navy captain, husband of former U.S. Representative Gabby Giffords
Eliminated in primary Bo "Heir Archy" Garcia (as a write-in candidate)
Withdrew Mohammad Arif, businessman and perennial candidate (write-in) (switched to Democratic general election write-in candidacy) Sheila Bilyeu, Democratic candidate for the 2020 United States Senate election in Oklahoma Juan Angel Vasquez
Declined Ruben Gallego, incumbent U.S. representative for Arizona's 7th congressional district (ran for re-election, endorsed Kelly) Katie Hobbs, Secretary of State of Arizona Grant Woods, former Republican Arizona Attorney General and former congressional chief of staff to former U.S. senator John McCain
Endorsements
Primary results
Libertarian primary Neither one of the write-in candidates received enough votes to secure the Libertarian nomination in the general election.
Write-in candidates Eliminated in primary Barry Hess, write-in Libertarian candidate in the 2018 United States Senate election in Arizona and Libertarian nominee in the 2014 Arizona gubernatorial election Alan White
Primary results
Other candidates General election write-in candidates Declared Republican Edward Davida John Schiess Debbie Simmons Patrick "Pat" Thomas
Democratic Mohammed "Mike Obama" Arif Adam Chilton Perry Kapadia Buzz Stewart
Other Christopher Beckett, veteran (Independent) William "Will" Decker (Independent) Matthew "Doc" Dorchester (Libertarian) Nicholas N. Glenn, Navy veteran and aerospace engineer (Independent Republican) Mathew Haupt (Independent) Benjamin Rodriguez (Independent) Joshua Rodriguez (Unity) Frank Saenz (Independent) Jim Stevens (Independent)
Withdrawn Robert Kay (Independent)
General election Debates Complete video of debate, October 6, 2020
Predictions SourceRankingAs of The Cook Political Report October 29, 2020 Inside Elections October 28, 2020 Sabato's Crystal Ball November 2, 2020Daily Kos October 30, 2020PoliticoNovember 2, 2020RCPOctober 23, 2020DDHQNovember 3, 2020538November 2, 2020EconomistNovember 2, 2020
Post-primary endorsements
Polling Graphical summary
Aggregate polls +Mark Kelly vs. Martha McSallySource of poll aggregationDates administeredDates updatedMark KellyMartha McSallyMargin270 to Win270 to WinNovember 2, 2020November 3, 202049.8%44.8%Kelly +5.0Real Clear PoliticsReal Clear PoliticsNovember 1, 2020November 3, 202050.5%44.8%Kelly +5.7Average 50.2%44.8%Kelly +5.4