Senator John McCain has been passed away from a particularly aggressive form of brain cancer called a glioblastoma. Although McCain has already had surgery that seems to have removed all of the worrisome tissue, the surgery only bought him some additional time. He passed away on August 25, 2018. McCain never retired and had been handling many aspects of his Congressional duties while still ill. Now that he has passed away, how will his replacement be chosen? Would his replacement be appointed or voted in through a special election?

Here’s what you need to know.

In Arizona, where McCain is Senator, vacancies are filled by governor appointment rather than a special election. This means that Gov. Doug Ducey, a Republican, would choose McCain’s replacement. In Arizona, the replacement must be from the same political party as the vacating Senator. So McCain’s replacement must also be a Republican.

Whoever Ducey selects would likely serve until 2020, the next general election after November 2018. If McCain had died or left office before May 30, then his replacement would have served until the general election in November 6, 2018 and his seat could have been on the ballot. In that situation, the person elected Senator would have held the position until McCain’s six-year term expires.

But because McCain lived past May 30, his replacement will fill out the remainder of his term until the next general election, Vox reported. McCain was just re-elected in the November 2016 election. Then the winner of the 2020 election would serve the remaineder of McCain’s term until 2022.

Ducey is up for re-election himself in 2018, so it’s likely he would be very cautious about who he picks. Many are suggesting that Kelli Ward would be the safest choice, since she got 39.2 percent in her primary run against McCain. She’s already signed up to run for election again in 2018, but this time she will be running against Sen. Jeff Flake.

Others have suggested McCain’s wife, Cindy McCain, as a possible appointment, The Phoenix New Times reported. The primary election is August 28, and Ken Bennett, who is also seeking the nomination against Ducey, has said that he promises he would not appoint Cindy McCain as the replacement.

I promise I will not appoint Cindy McCain to US Senate as Gov of AZ. #bennettforgov — Ken Bennett (@BennettArizona) May 31, 2018

Other names floated as possible replacements for McCain include Kirk Adams, Ducey’s chief of staff, Barbara Barrett, chairman of the Aerospace Corporation, or Jon Kyl, who served in the senate alongside McCain from 1995 to 2013.

McCain was serving his sixth term as Senator when he passed away. His election this year was described as “bruising” by the New York Times, as he campaigned against Democrat Ann Kirkpatrick. In 2013, he had hinted that he might retire, but he changed his mind and ran a successful campaign.