The governor’s choice to replace the late senator – from a Republican field including his widow – will be the first test of McCain’s legacy

As the US mourns John McCain, the governor of Arizona must consider the political implications of his death. Chief among them: who will be appointed to fill his Senate seat?

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McCain died last month, after a year-long battle with brain cancer, at the age of 81. Doug Ducey, the Republican governor of Arizona since 2014, has said he will not appoint a successor until the senator and 2008 presidential nominee has been buried. That will happen at the US Naval Academy in Annapolis, Maryland, on Sunday.

While McCain was alive, Ducey, who is running for re-election himself in what could be a competitive race, avoided discussing the issue. He has also sharply admonished any Republicans engaging in conjecture and has not given any public indication of who he will choose – only that he will not appoint himself.

At a memorial service at the capitol in Phoenix on Wednesday, Ducey called McCain the state’s “favorite adopted son” and said imagining life without him was like “picturing Arizona without the Grand Canyon”.

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“Make no mistake, he fought like hell for the causes he believed in,” Ducey said, adding: “John McCain’s fight for America isn’t over.”

Under Arizona law, the governor must choose someone from the senator’s party. The appointee will serve until 2020, when a special election will be held to fill the remainder of the six-year term, to January 2023.

According to three Arizona Republicans who spoke on condition of anonymity, possible picks include Jon Kyl, a former senator who served alongside McCain; former congressman John Shadegg; state treasurer Eileen Klein, who Ducey appointed earlier this year; and Cindy McCain, the senator’s wife of 38 years.

In his own tribute, Kyl recalled traveling the world with McCain. His friend was “a strong force for America in the world”, he said. “John McCain believed in America. He believed in its people, its values and its institutions.”

Klein, who one Republican said was a serious contender, was also present, seated with two serving senators: Dean Heller, a Republican from Nevada, and Brian Schatz, a Democrat from Hawaii.

Facebook Twitter Pinterest Cindy McCain could be a contender to fill her late husband’s Senate seat. Photograph: Andrew Harnik/AFP/Getty Images

Barbara Barrett, the chair of the Aerospace Corporation and a former US ambassador to Finland, and Kirk Adams, the governor’s chief of staff and a former state lawmaker, are also thought to be possible picks. The Arizona Republic newspaper has also named former congressman Matt Salmon and businesswoman Karrin Taylor Robson.

State Republicans said Ducey was likely to appoint someone who would run in 2020, as opposed to a caretaker. But Cindy McCain should not be ruled out, one said, emphasizing Ducey’s affection for the family.

“If she gave him any indication she wants the seat, I think she gets it,” the source said.

The choice comes at a tumultuous time for Arizona Republicans, as the pragmatic policies championed by McCain during his 36 years in Washington are challenged by the very tribal and nationalist politics against which the senator railed.

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Republicans hold a 50-49 majority in the Senate and confirmation hearings for Donald Trump’s second supreme court nominee, Brett Kavanaugh, are due to begin next week. The majority leader, Mitch McConnell, has little room for error.

This is also a midterm election year and in Arizona, Republican dominance appears to be weakening. Trump won the state by just over 3%, the smallest win for a Republican since Bill Clinton won Arizona in 1996.

Furthermore, Arizona Republicans are already fighting to defend the state’s other Senate seat, which will be vacated by Jeff Flake. Like McCain, the junior Arizona senator alienated conservative voters with criticism of Trump.

On Wednesday, in a moment of levity in an otherwise somber ceremony, Ducey recalled one of his final conversations at McCain’s Hidden Valley ranch, near Sedona.

McCain wisecracked: “My biggest challenge is deciding whether to run for re-election in 2022.”