Kyl wrote a letter dated Dec. 12 to Ducey, informing him of his resignation. The letter was hand-delivered to the Governor’s Office late Thursday afternoon.

“Thank you for appointing me to the U.S. Senate to fill the vacancy created by John McCain’s death,” Kyl wrote. “It has been an honor and a privilege to again serve the people of Arizona.

“When I accepted your appointment, I agreed to complete the work of the 115th Congress and then reevaluate continuing to serve. I have concluded that it would be best if I resign so that your new appointee can begin the new term with all other Senators in January 2019 and can serve a full two (potentially four) years. Therefore, I will resign from the U.S. Senate effective 11:59 p.m. EST December 31, 2018.”