When Kyl takes office, he will restore the GOP's 51-49 seat majority in the Senate. That margin is critical now as the GOP seeks a majority vote to confirm Supreme Court nominee Brett Kavanaugh. Kyl was charged with helping Kavanaugh navigate the confirmation process in the Senate, and "now, Sen. Kyl can cast a vote for Kavanaugh's confirmation," Ducey said Tuesday.

"We're all saddened by the circumstances that required this appointment and appreciate that there was only one John McCain," Kyl said, adding that he wants to take care of "unfinished business" before the Senate including judicial nominations.

Kyl served his entire tenure in the Senate alongside McCain and spent time as the chamber's second-ranking Republican. McCain, 81, the longtime Republican senator and former GOP presidential nominee, died late last month after a struggle with brain cancer.

At a news conference Tuesday, the Republican governor said Kyl committed to serve through the end of the year and added that he hopes the ex-lawmaker will serve longer. Kyl, 76, represented Arizona in the Senate for nearly two decades before retiring in 2013. He stressed that he "will not seek this seat in 2020" in a planned special election.

"Arizona needs someone who can hit the ground running on day one, and that's Jon Kyl," he said.

Since leaving the Senate, Kyl has been a lobbyist at the firm Covington & Burling, where he has most often represented the pharmaceutical industry, according to the Center for Responsive Politics. It is unclear how much Kyl will distance himself from the lobbying business while he serves in the Senate.

Kyl is expected to be a more reliable vote for GOP leadership than McCain was. While McCain largely voted with his party, he notably broke with the vast majority of Republicans by opposing an effort last year to repeal large parts of the Affordable Care Act.

In a tweet, McCain's widow Cindy said, Kyl "is a dear friend of mine and John's."

"It's a great tribute to John that [Kyl] is prepared to go back into public service to help the state of Arizona," she wrote.

McCain tweet

In a tweet, Arizona's other senator — Republican Jeff Flake — said, "there is no one more qualified and Arizona is well served" by Ducey's choice of Kyl.

Flake tweet

The governor appeared to walk a fine line in trying to appease his state's more pro-Trump Republican Party and picking someone who would walk the path of McCain, who frequently criticized Trump. Even a memorial service for the senator this weekend featured rebukes of the president.

Flake, who will retire in January, has also spoken out against Trump more often than his GOP colleagues. The race for his seat in Arizona is one of this year's most important.

Whoever wins the 2020 special election will have to face election again in 2022 at the end of McCain's term.

On Tuesday, Kyl said he does not "really have a relationship with President Trump" and only met him once. In a tweet later in the day, the president said Kyl "will be an extraordinary Senator representing an extraordinary state."

"I look forward to working with him!" Trump tweeted.

Trump tweet