Popp was the Deputy Principal Officer and then Acting Principal Officer at the United States Consulate General in Sao Paulo, Brazil. He also served as the Deputy Economic Counselor of the United States Embassy in Bogota, Colombia. He served as the Political Counselor and then as the Acting Deputy Chief of Mission at the United States Embassy in Nairobi, Kenya. He was also the Director of the Office of Regional Economic Policy and Summit Coordination in the Bureau of Western Hemisphere Affairs at the State Department. He was the Chargé d'Affaires a.i. in Brazil from November 2018 to February 2020.[4] He has been the Deputy Chief of Mission at the U.S. Embassy in Brasilia, Brazil since August 2017.[3]
Ambassador to Guatemala
On May 28, 2020, President Trump announced his intent to nominate Popp to be the next United States Ambassador to Guatemala. On June 2, 2020, his nomination was sent to the United States Senate.[5] He was confirmed by the U.S. Senate on August 6, 2020 by voice vote.[2] He was sworn into office on August 13, 2020.[6] Popp presented his credentials to Guatemalan President Alejandro Giammattei on October 19, 2020.[7]
Ambassador to Uganda
On February 27, 2023, President Joe Biden nominated Popp to be the next ambassador to Uganda.[8] Hearings on his nomination were held before the Senate Foreign Relations Committee on May 16, 2023. The committee favorably reported the nomination on June 1, 2023. It was confirmed by the full Senate on July 27, 2023 via voice vote.[9] Popp presented his credentials to President Yoweri Museveni on September 20, 2023.[10]