Former U.S. Sen. Jon Kyl, the longtime Arizona Republican who spent nearly three decades representing the state in Congress and rose to become the Senate’s No. 2 Republican, died Thursday at 84.

Kyl’s family said he died from complications of a neurological disease. In December 2025, Kyl announced that he had been diagnosed with a neurological disease manifesting as dementia and was withdrawing from public life.

“We know that Jon belonged to all of Arizona, a state he loved and explored with vigor, curiosity, and wonder,” his family said Thursday. “Serving his state and nation in Congress was a privilege and responsibility he honored and respected.” Memorial services will be announced later.

Tributes streamed in from across the political spectrum. Governor Katie Hobbs posted on X, “Arizonans are mourning the loss of former U.S. Senator Jon Kyl. Throughout his decades of public service in the House and Senate, he was a dedicated statesman who always cared deeply for our state. My thoughts and deepest condolences are with his family and loved ones.” Her opponent, Rep. Andy Biggs, posted a long Tweet that began, “Senator Jon Kyl was an exemplary public servant who understood Arizona, fought tirelessly for our interests, and approached his responsibilities with humility and conviction.”

Kyl, a Republican, represented Arizona’s 4th Congressional District in the U.S. House from 1987 through 1994 before winning election to the Senate in 1994. He served three terms in the Senate, from 1995 until his retirement in January 2013, and served as Republican whip from 2007 through the end of his tenure.

He briefly returned to Washington in 2018 after Gov. Doug Ducey appointed him to the Senate seat left vacant by the death of John McCain. The Senate swore in Kyl  on Sept. 5, 2018, and served until his resignation at the end of that year.

Over his career, Kyl became closely associated with Arizona water policy, tribal water-rights settlements and national security issues. He served on Senate committees including Judiciary, Finance, Intelligence and Armed Services and played a role in the 2018 confirmation of Supreme Court Justice Brett Kavanaugh. Arizona State University later named its Kyl Center for Water Policy in his honor.

Born in Nebraska in 1942 and raised in Iowa, Kyl came to Arizona to attend the University of Arizona, earning his undergraduate and law degrees there. He later practiced law in Phoenix before beginning his congressional career. His father, John Henry Kyl, had previously served as a Republican congressman from Iowa.

Kyl was 84.