Longtime Republican Senator Pat Roberts of Kansas will not seek re-election in 2020, setting up an intense political scramble to replace him.

Roberts reviewed a congressional career that included eight farms bills and what he described as success in improving national intelligence after the Iraq war as he announced that he won’t seek re-election in 2020.

Roberts spoke Friday at the Kansas Department of Agriculture campus near Kansas State University, his alma mater, surrounded by supporters and family.

Roberts spent 16 years in the U.S. House and has been in the Senate for 22 years, but faced some pressure to step aside in part because he will be 84 next year. He also faced grueling primary and general election contests in 2014.

On Friday he expressed gratitude for friends and supporters over decades in public life.

“Never in my wildest dreams did I think I would become the longest serving member of congress in this state’s history,” Roberts said.

Roberts began his Capitol Hill career as an aide in 1967. He won a U.S. House seat representing western Kansas in 1980 and was elected to the Senate in 1996. But his longevity became a liability during his 2014 campaign.