Middendorf has served a number of presidential administrations in high-level positions, including Secretary of the Navy and Ambassador to the European Communities, the Organization of American States, and the Netherlands. A delegate to presidential nominating conventions as far back as Barry Goldwater's in 1964, Middendorf remains active in shaping conservative foreign, defense and economic policy through regular meetings with staff members on Capitol Hill.

An intellectual force behind the North American Free Trade Agreement, having written about the concept of a free-trade area uniting the region as early as 1988 in Heritage's "Mandate for Leadership III," Middendorf also is a true renaissance man with interests in both music—he wrote Heritage's theme march—and art.