Georgia Senator Johnny Isakson, 74, announced this week that he will step down at the end of the year, citing his declining health.

“After much prayer and consultation with my family and my doctors, I have made the very tough decision to leave the U.S. Senate at the end of this year. I have informed Georgia Governor Brian Kemp today that I will resign my Senate seat effective December 31, 2019,” Isakson said in a statement.

Isakson underwent two back surgeries in 2017 and fractured his ribs during a fall in his Washington, D.C., apartment last month.

Isakson’s term runs through 2022, and Kemp, under state law, is allowed to fill the vacant Senate seat.

A special election will be held to fill the remaining two years of Isakson’s term during the next regularly scheduled election. Georgia voters will now cast ballots for both of the state’s Senate seats in 2020, when Sen. David Perdue (R-Ga.) is also up for reelection.