In the
1996 presidential election, Yamassoum directed President
Idriss Déby's campaign. After serving as President of the
Constitutional Council, he was named Prime Minister of Chad on December 13, 1999; he had also previously served as Minister of Education and Minister of Culture. He served as Prime Minister until June 12, 2002, when he resigned and was replaced by
Haroun Kabadi. In June 2003, when Kabadi's government resigned and a new government led by
Moussa Faki took office, Yamassoum was appointed as the Minister of State for Foreign Affairs. He left that position in August 2005 when a cabinet reshuffle occurred. Yamassoum was appointed as chairman of the Board of the
Hydrocarbons Company of Chad (
Societe des Hydrocarbures du Tchad, SHT) in November 2007. Later, as Secretary-General of the
Patriotic Salvation Movement (MPS), Yamassoum was entrusted with leading the ruling party into 2011, a major election year—both parliamentary and presidential elections were planned. Critics argued that he lacked popularity with the party base. Yamassoum was subsequently appointed as President of the Constitutional Council. He headed the court when it validated the results of the
April 2016 presidential election, in which Déby won re-election in the first round, on 4 May 2016. In 2019, he became the first chairman of the newly created
Central African Financial Market Supervisory Commission, a position he held until 2023. ==References==