Alfonso E. Lenhardt represented the United States as Ambassador to Tanzania from 2009 to 2013. He was also accredited as the US representative to the East African Community (EAC) in 2010. He left his post in October 2013. From 2001 to 2003, he served as Sergeant at Arms of the United States Senate. From 1965 to 1997, he had a distinguished military career in the U.S. Army, with multiple assignments to various parts of the world, retiring as a highly decorated Major General.

The sergeant at arms and doorkeeper of the United States Senate is the protocol officer, executive officer, and highest-ranking federal law enforcement officer of the Senate of the United States. The office of the sergeant at arms of the Senate currently has just short of 1,000 full time staff.