PHOENIX (AP) — Sen. John McCain’s legacy was thrust into focus nearly one year ago when he announced his brain cancer diagnosis. The six-term Senator and decorated Vietnam War veteran is now fighting the illness from his beloved Arizona, and filling the role of one of the few Congressional Republican voices to publicly rebuke Trump administration decisions.

Yet the question of what happens if McCain steps down from office before 2022 is a lingering one, casting an uncomfortable haze around the future of a seat that can’t quite ever be filled.

“John McCain is a one-of-a-kind politician, and there’s no replacing him,” said Stan Barnes, an Arizona Republican consultant. “No one serving in political office today remembers a time when John McCain was not representing us in Washington.”

Some Arizona Republicans have criticized conversations about the future of McCain’s seat as inappropriate. But reflections around the 81-year-old statesman’s life, legacy and status as a national political figure have resurfaced via a new HBO documentary, “John McCain: For Whom the Bell Tolls,” and his new memoir, “The Restless Wave.”

The McCains have a family retreat south of Sedona, Arizona, along tree-lined Oak Creek. Daughter Meghan McCain was married there.

She said on KTAR’s Mac and Gaydos radio show Tuesday that she’s been trying to visit her father every other weekend. She said he’s strong, walking, talking and hanging in there.

“Everybody’s just dealing with it the best they can,” Meghan McCain said.

Following a decorated military career that included spending more than five years in prison camps, McCain entered the political arena in the early 1980s. He went from the House of Representatives to being elected to the Senate in 1986, following Barry Goldwater who retired. McCain gained a reputation as a lawmaker who was willing to stick to his convictions rather than go along with party leaders. It is a streak that draws a mix of respect and ire.

Matt Salmon, a former Arizona congressman, said McCain was instrumental in his own political career —along with countless other Arizona Republicans. Much like Goldwater, McCain’s been “the godfather of Arizona politics” for decades.

Salmon said McCain exemplifies how to stand up for one’s convictions and constituents regardless of the wants of party leadership. During the late 1990s, Salmon drove a successful effort to remove Newt Gingrich as Speaker.

“I don’t know that I would’ve had the courage to go do something like that without a maverick like John McCain paving the way,” he said.

When Salmon was elected to Congress, McCain, as a mentor, was supportive, loyal and quick to share his dry sense of humor.

“He said to me, ‘Congratulations Matt, now you’re part of the problem,'” Salmon said.

McCain’s maverick ways have pressed on in the era of President Donald Trump. He continues to release statements and tweets from Arizona. Following Trump’s decision to not endorse a G7 statement with other global trade leaders, McCain tweeted a message to U.S. allies that said in part “Americans stand with you, even if our president doesn’t.”

Sen. Jeff Flake, Arizona’s junior senator who is not running for re-election, said McCain’s mantra of “country before party” sets him apart from other senators. Flake praised his honesty and transparency, as witnessed in the recent documentary.

“He was open about his mistakes, and his failings, and that’s part of what’s so endearing about him,” he said.

Flake said during a recent visit with McCain at his home, the two sat on the deck for about an hour and talked about what they miss about Arizona politics, the kind that put party and partisanship aside. Flake said he’s concerned that Arizona voters may miss out on having an independent voice that they’ve grown accustomed to when McCain is no longer in office.

“Today’s politics kind of reward those who stick with the crowd,” Flake said. “The incentives are not here to be independent and it takes a strong personality, like John, kind of an outsized personality, to pull that off.”

Former Arizona congressman John Shadegg said most lawmakers don’t work as hard as McCain. He cited town hall meetings in Arizona that McCain held in non-campaign years. One time at Phoenix’s Sky Harbor Airport, Shadegg was speaking with McCain but had to cut the conversation short when “about a hundred people” came over to talk to the senator.

“There’s a personal side to John McCain, which is very different than the public John McCain, and one that you can’t help but like and respect,” Shadegg said.

Some of the state’s Republican voters have been critical of McCain for not being conservative enough. In 2016, primary challenger Kelli Ward came within 11 percentage points in a four-way race after running as a more conservative alternative. A few years before that, a censure effort from the state party called out McCain for campaigning as a conservative but voting more moderate.

On the flip side, McCain’s service and his ability to stick to his convictions have earned him respect from Democrats. McCain’s vote against a repeal of the Affordable Care Act shortly after he announced his diagnosis further endeared him to those who might disagree with him on other policies, Democratic consultant DJ Quinlan said.

“He did have his high profile moments where he was really willing to stick it to his party,” Quinlan said.

In the event McCain steps down from his Senate seat before 2022, state law requires the governor to fill a vacancy with an appointee of the same political party who will serve until the next general election. Republican Gov. Doug Ducey hasn’t been keen on speculating. He and his wife Angela visited John and Cindy McCain about two weeks ago.

“To anyone who uses this as an opportunity to speculate or fan the rumor mill: Washington DC’s obsession with this when there is no issue to be discussed is disgraceful,” Ducey spokesman Daniel Scarpinato said in a statement.

Yet rumors abound, with names being suggested as possibilities to fill the seat as an appointee, such as Cindy McCain, former Sen. Jon Kyl and former state attorney general Grant Woods.

Republican consultant Barnes called replacement rumors “desperate barbershop gossip,” though he said he understands the uncertainty some might have about the exit of such a dominant figure from the political stage.

“That particular Senate seat has been an outsized, powerful voice on the floor of the United States Senate, and you just can’t overstate the importance of that phenomenon,” Barnes said.

Some had wondered whether McCain’s seat would be up this year if he left office before May 30, the deadline for candidates to file signatures to get on the ballot. That opportunity is likely closed — meaning the next general election where a candidate could run for the seat would be 2020 instead of 2018. Secretary of State Michele Reagan’s office has said her office won’t speculate on responses to possible vacancies, and will make any decisions once a vacancy becomes available.

Salmon said he doesn’t think anyone can fill McCain’s shoes. He recalled a trip to Vietnam where he saw a monument to McCain.

“His voice is not just an Arizona voice,” he said. “It’s a world voice.”

He said many are wishing McCain well and hoping for the best.

“He’s one of the toughest guys I’ve gotten to know,” Salmon said. “It’s not a disease that most people diagnosed with are successful at fighting. But they’re not John McCain. He’s a fighter.”