Gov. Doug Ducey will pick a Republican to finish the term for the seat held for 30 years by the late Sen. John McCain.

That much is clear.

But who he will appoint to succeed Jon Kyl, who has filled the seat since September, is not yet known.

The governor and some of his closest aides are not talking. Outgoing U.S. Rep. Martha McSally and former Ducey chief of staff Kirk Adams are two potential appointees drawing intense speculation in political circles in Washington and in Arizona.

Others are mentioned, including highly regarded state Treasurer Eileen Klein. And it is unknown if Ducey has had discussions about a potential appointment with McCain's widow, Cindy McCain.

Whoever the selection, Arizona soon will have the most junior pair of senators in the country.

Here are three names that are being discussed as potential appointees:

Martha McSally

The two-term congresswoman who represents a Tucson-area district lost her bid for the state’s other Senate seat to Democrat Kyrsten Sinema and earlier this week gave her farewell speech in the House of Representatives. This opening could give her new political life.

McSally's showing in November may provide the governor with a measure of confidence that she could win if given another shot.

But that pick could anger an array of voters, from liberals and independents who rejected McSally in November to conservatives who view her as having blocked former state Sen. Kelli Ward from exciting the GOP base. If McSally loses again in 2020, it could spark a new round of Republican recriminations.

Senate Majority Leader Mitch McConnell, R-Kentucky, supported McSally and important Republican donors spent millions of dollars on her election effort and likely want to see that investment pay off. Ducey and McSally share some of the same deep-pocketed donor base.

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McSally once worked for Kyl and considers him a political mentor.

Her biography as the nation’s first female combat pilot is compelling.

But McSally tethered herself throughout the 2018 election cycle to President Donald Trump and a national hard-right playbook instead of one that reflected the state’s more nuanced electoral landscape. Her Missouri-based campaign consultants blamed her loss on media coverage, Trump's favorability, outspending by Sinema and her allies, and Sinema’s lack of a competitive primary, among other factors. The campaign did not take ownership of the loss, according to a post-campaign memo obtained by the Washington Post.

Ben Domenech, publisher of conservative web magazine The Federalist and husband of Meghan McCain, tweeted Friday that McSally would be an "unwise choice."

In August, McSally drew controversy over her words about a national defense authorization act named after Meghan's dad John McCain, who won six terms as a U.S. senator from Arizona and was a former prisoner of war.

It was officially called the John S. McCain National Defense Authorization Act for Fiscal 2019. At an event at which President Donald Trump signed the act and in numerous public comments about it, McSally did not use McCain's name.

At the time, Meghan McCain called her out. McSally followed up by tweeting that McCain, as chairman of the Senate Armed Services Committee, "helped our troops and strengthened our country's national security."

McSally met with Cindy McCain Friday afternoon at her north Phoenix home, according to Republicans familiar with the conversation.

In the meeting, McSally apologized to McCain's widow for not mentioning the senator’s name during Trump's signing of the bill.

Cindy McCain expressed her appreciation for the apology and conveyed the importance of her late husband’s legacy and his service to Arizona, they said.

Kirk Adams

One of Ducey's most trusted advisers, the former speaker of the Arizona House of Representatives, has been the governor's wingman for the past four years.

As Ducey's chief of staff, Adams was at the table and on sensitive phone calls with legislative leadership on issues ranging from tax policy to health-care reform. And he was Ducey's point man on strengthening Arizona's relationship politically and economically with Mexican officials on the border and in Mexico City following Gov. Jan Brewer's administration.

After Ducey won re-election, Adams announced he was stepping down. His last day on the job was scheduled to be Friday.

Adams would not discuss his future plans in detail.

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Adams has close relationships with influential Republican donors who may be willing to heavily invest in someone who shares many of the same policy ideals.

An Adams appointment was once viewed as potentially risky for Ducey, but his name has been back in circulation since McSally's loss.

When Jeff Flake, Arizona's other outgoing U.S. senator, ran for his seat in 2012, Adams ran for the East Valley House seat that Flake was leaving.

Adams, who had been House Speaker in the Arizona Legislature, lost the Republican primary to former U.S. Rep. Matt Salmon. After two years as a lobbyist, Adams caught on with the newly elected Ducey.

Adams is perhaps best known as the principal author of the state’s 2011 tax cut legislation that slashed corporate collections. He also supported Arizona’s controversial 2010 immigration-enforcement law, Senate Bill 1070.

Adams and Sinema worked together at the state Legislature years ago, and they remain friends.

Eileen Klein

The state treasurer and former chief of staff to Brewer, Klein has deep experience in state government and Arizona politics.

The governor appointed her as state treasurer in April after Republican Jeff DeWit accepted a job with Trump's administration.

She served on Ducey's transition team in 2014 after his first gubernatorial win.

Before he appointed her as treasurer, Klein was president of the Arizona Board of Regents, which governs the state's universities.