While King's seat is competitive, he suggested his decision to step down was not driven by fear of a challenger in next year’s election, citing his support in public polling and a formidable campaign war chest.

“Politically I will miss the energy and dynamism of a re-election campaign especially since my polling numbers are as strong as they have ever been and I have more than $1 million in campaign funds,” he said.

King won reelection in 2018 by 6 percentage points, down sharply from his 17-point margin in 2016. President Donald Trump carried his district — which runs along the South Shore of Long Island and includes parts of Nassau and Suffolk counties — by 9 points in 2016, but former President Barack Obama won it twice before that.

King's daughter, Erin King Sweeney, a Hempstead town councilwoman, was long thought to be a possible successor for her father's seat in Congress. But King Sweeney announced earlier this fall that she was moving to Charlotte, N.C., pausing her political career.

Before exiting Congress, King said he intends to vote against Trump’s impeachment as part of the Democratic-led House inquiry, and will support the president’s bid for a second term in 2020.

Including King, 20 GOP House members have made public their plans to retire at the end of this Congress, including a handful of Republican committee leaders.