PHOENIX (AP) — Former Republican U.S. Sen. Jon Kyl of Arizona on Tuesday announced his withdrawal from public life following a dementia diagnosis.

Kyl, 83, represented Arizona in both chambers of Congress for nearly three decades. Most of those years were in the Senate including a term as minority whip.

“My family and I now head down a path filled with moments of joy and increasing difficulties,” Kyl said in a statement. “I am grateful beyond expression for their love and support, in these coming days as in all the days of my life. Despite this diagnosis, I remain a very fortunate man.”

Kyl left the Senate in 2013 and joined the lobbying firm Covington and Burling. In 2018 he was appointed by then-Gov. Doug Ducey, a fellow Republican, to fill the vacancy caused by the death of former Sen. John McCain. Kyl served several months before rejoining the lobbying firm.

Kyl leveraged his expertise on water policy in Congress to gain approval of tribal water rights settlements, said Sarah Porter of Arizona State University. He was an “important participant” in negotiations that created the state’s water rules, said Porter, director of the university’s Kyl Center for Water Policy that is named after the former senator.

As a lobbyist, Kyl helped guide the confirmation of U.S. Supreme Court Justice Brett Kavanaugh.