Former Senator Jon Kyl will fill the late Senator John McCain’s seat in the US Congress, Arizona Governor Doug Ducey has said.

The appointment marks an unexpected return to Capitol Hill for Mr Kyl, who retired in 2013 after serving three terms an Arizona senator. Mr Doucey said he expected the 76-year-old to “hit the ground running", adding that now was “not the time for newcomers”.

“There is no one in Arizona more prepared to represent our state in the US Senate than Jon Kyl,” Mr Ducey said in a statement. “He understands how the Senate functions and will make an immediate and positive impact benefiting all Arizonans."

The appointment expires in November 2020, when a special election will be held to replace Mr McCain, who died last month from an aggressive form of brain cancer. But Mr Kyl has promised only to serve until the close of this Congressional session, which ends in January 2019. He also said that he has no plans to run again in 2020.

"I’m accepting this appointment to fill the seat vacated by the passing of my dear friend because of my sense of duty to the state I love, and the institution of the Senate which I served for 18 years, and because the governor asked for my help," Mr Kyl said at a press conference, according to AZ Central.

John McCain: US Senator in pictures Show all 40 1 /40 John McCain: US Senator in pictures John McCain: US Senator in pictures John McCain - 2000 John McCain waves to crowds at The University of Portland in Oregon. McCain was campaigning for Republican nominee George W. Bush AFP/Getty John McCain: US Senator in pictures John McCain - 1967 Senator John Mccain In A Hanoi Hospital During The Vietnam War November, 1967 Getty John McCain: US Senator in pictures John McCain - 1993 John McCain, a former POW, looks at a display of personal belongings of American POWs at the joint POW/MIA archives center in the Hanoi Army Museum AFP/Getty John McCain: US Senator in pictures John McCain - 1999 Republican Senator John McCain announces his official bid for the 2000 White House in Nashua, New Hampshire. Evoking five years as a prisoner of war in Vietnam, McCain highlighted his own sacrifice and his 17-year record of public service in the US Congress AFP/Getty John McCain: US Senator in pictures John McCain - 1999 Republican presidential candidate John McCain poses with an A-4 jet -- similar to the one which he was piloting when he was shot down during the Vietnam War -- on the deck of the USS Intrepid aircraft carrier in New York. 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Roll United States Courthouse Bill into law in the Oval Office of the White House as Homeland Security Secretary and former Arizona Governor Janet Napolitano, Senator John McCain, Chief of Staff to Rep. Gabrielle Giffords Pia Carusone, Rep. Ed Pastor, and Rep. Trent Franks look on. President Obama signed the bill to name a new federal courthouse in Yuma, Arizona, after federal Judge John M. Roll, who was gunned down during the shooting rampage in Tucson, Arizona Getty John McCain: US Senator in pictures John McCain - 2012 Republican presidential candidate and former Massachusetts Governor Mitt Romney talks with former presidential nominee US Sen. John McCain on Romney's campaign bus with Press Secretary Andrea Saul in between events near Manchester, New Hampshire. 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"The free world is with you, America is with you, I am with you... Ukraine will make Europe better and Europe will make Ukraine better." AFP/Getty John McCain: US Senator in pictures John McCain - 2013 US Senators Lindsey Graham and John McCain meet with Israeli Prime Minister Benjamin Netanyahu in Jerusalem, Israel GPO/Getty John McCain: US Senator in pictures John McCain - 2014 John McCain hugs Debbie Valle after speaking at a forum at the Burton Barr Central Library in Phoenix, Arizona. McCain met with Arizona Veterans to discuss mismanagement of Veterans Affairs Getty John McCain: US Senator in pictures John McCain - 2014 John McCain and wife Cindy attend a MLB game between the Arizona Diamondbacks and the Los Angeles Dodgers at Chase Field in Phoenix, Arizona. Getty John McCain: US Senator in pictures PHOENIX, AZ - NOVEMBER 08: Sen. John McCain (R-AZ), center, and his wife Cindy (R) greet supporters after casting their vote at the Mountain View Christian Church polling place on November 8, 2016 in Phoenix, Arizona. Throughout the country, millions of Americans are casting their votes today for either Hillary Clinton or Donald Trump to become the 45th president of the United States. (Photo by Ralph Freso/Getty Images) Ralph Freso Getty Images John McCain: US Senator in pictures John McCain - 2015 WASHINGTON, DC - MAY 05: Sen. John McCain (L) (R-AZ) and Sir Elton John, Founder, Elton John AIDS Foundation, pose for a photo before an Elton John AIDS Foundation and The ONE Campaign hosted reception on global HIV/AIDS funding at the U.S. Capitol Visitor Center on May 5, 2015 in Washington, DC. 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The decision was praised by current Arizona Senator Jeff Flake, as well as Mr McCain’s widow, Cindy McCain.

“Jon Kyl is a dear friend of mine and John’s,” Ms McCain tweeted. “It’s a great tribute to John that he is prepared to go back into public service to help the state of Arizona.”

The move will not be a dramatic one for Mr Kyl, who has worked for the past five years at Washington-based lobbying firm Covington & Burlington. He has been a familiar face on Capitol Hill since leaving Congress, helping nominees like Attorney General Jeff Sessions prepare for their Senate confirmation hearings, according to Roll Call.

Mr Kyl has been shepherding Supreme Court nominee Brett Kavanaugh through the same process in recent months, and – in an interesting twist – may wind up voting on Mr Kavanaugh's confirmation upon returning to Congress. He is expected to be a reliable conservative vote for President Donald Trump on that issue, and on many to come.

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Mr Kyl started his career as an attorney in Phoenix, and joined Congress as a representative from Arizona in 1986. He became a senator eight years later, and worked his way up to the No 2 position of Senate Minority Whip – a position he held for six years.

One of Mr Kyl’s most infamous moments in Congress came in 2011, when he argued against providing federal funding for Planned Parenthood.

Speaking on the Senate floor, Mr Kyl claimed abortions made up “well over 90 per cent” of the services the women’s health clinics provided. Confronted with the fact that abortions make only 3 per cent of the Planned Parenthood’s work, Mr Kyl’s office claimed the senator’s words were "not intended to be a factual statement".