Senate Sergeant at Arms Terrance Gainer, the chamber's top law enforcement official, will step down this spring after seven years on the job, Senate Majority Leader Harry Reid said Thursday.

"Terry has spent 47 years of his life dedicated to law enforcement at the federal, state and city level and throughout his years of military service," the Nevada Democrat said. "Terry is one of the finest public servants I have ever met and I am grateful for all he has done for our community."

Gainer will depart as the longest-serving Senate sergeant at arms — which also heads Senate protocol — since World War II and the first to have held both that position and that of Capitol Police chief.

Reid said Gainer led "dramatic" safety improvements in the Capitol complex, including upgrades to its emergency communication system and information technology infrastructure, and new services for senators, their staffs and constituents.

"Serving the Senate family and the Capitol community has been a rare privilege," Gainer said. "The Sergeant at Arms organization continues to exceed expectations."

Replacing Gainer will be current Deputy Sergeant at Arms Drew Willison, who has spent most of the past seven years as Gainer's No. 2 after several years as a senior staffer on the Senate Appropriations Committee.

Michael Stenger will be appointed as the next deputy sergeant at arms. He came to the sergeant at arms in 2011 after a 35-year career in the Secret Service.