Thongsing was first appointed as Lao Prime Minister after a cabinet reshuffle in December 2010.
Thongsing was born on April 12, 1944, in Xoneneua village, Vienthong district of Laos' northeast province of Huaphan.
Thongsing joined the revolutionary movement on Aug. 18, 1959, becoming a member of the LPRP on July 12, 1967.
From 1952 to 1958 he was a student in Xamneua district, Huaphan province, then became a military medical student and served on the battlefield in the Laos-Vietnam border area from 1959-1960.
He attended cultural training from 1960 to 1963 before becoming Deputy Director of Xamneua Secondary School, director of the junior secondary school and director of the Education Department in Xiengkhor district, Huaphan province.
From 1971 to 1976, he was director of the senior secondary school and teacher training school in Sopbao, Viengxay district in Huaphan province.
From 1976 to 1979 Thongsing held several positions at the Ministry of Education as Deputy Director and subsequently Acting Director of the Personnel and Organisation Department, and Deputy Director of the Vocational Education Department.
Thongsing studied politics and administration from 1980 to 1981 before becoming a standby Party Central Committee member as well as President of the Newspaper and Radio Committee and Deputy Head of the Party Propaganda and Training Board from 1982 to 1983.
From 1983 and 1988, Thongsing served as Minister of Information and Culture. From 1989 to 1991, he was Party Secretary and Vice President of the People's Supreme Assembly, and was promoted to Acting President of the Assembly from 1991 to 1992.