(1994–1998). Serpa was later elected to the National Constituent Assembly in 1991 in which he shared a collegiate presidency with Antonio Navarro Wolff (former member of the M-19 guerrillas) and Álvaro Gómez Hurtado (representative of the Conservative Party) to create the Colombian Constitution of 1991. After the creation of the new constitution Serpa continued as President of Liberal Directorate in Santander Department and President of the Central Politics Commission of the Liberal Party. He was then prospect for presidential candidate in 1998, but was shaded by Ernesto Samper. Serpa was then elected National Director of the Liberal party for the period 1998 to 1999. During the government of Álvaro Uribe, Serpa was appointed ambassador of Colombia to the Organization of American States (OAS) and he also disputed the presidential bids of 2002 and 2006. 8000 Process involvement In 1981 Serpa met Ernesto Samper Pizano, who was working as debate chief of Alfonso López Michelsen's second presidential campaign and became good friends. For the presidential campaign of 1990 Samper became a candidate and Serpa collaborated with his efforts in the Santander Department, his region of influence, while being the leader of his movement: the FILA. But Samper lost the elections. In the 1994 elections, Serpa became Debate Chief of Samper's presidential campaign and this time Samper was elected president of Colombia. On 20 June 1994, the opposing presidential candidate Andrés Pastrana then made public the Narcocassettes a series of telephone recordings in which members of the Cali drug cartel mainly journalist Alberto Giraldo talked with Gilberto and Miguel Rodríguez Orejuela regarding the financing of the Samper campaign for the presidency. The Supreme Court then opened an investigation which was dubbed the Proceso 8000. Serpa defended Samper against these allegations of drug money entering the campaign in which he was also involved. The relations with the United States government a major contributor to the drug effort in Colombia deteriorated. Samper and most of his collaborators were absolved from any wrongdoing with the exception of Fernando Botero and Santiago Medina. But the scandal involved a dozen members of Congress and numerous politicians and businessmen with the Cali cartel. After this incident Serpa's credibility maintained a low level with Colombians for supporting Samper, as well as responding to criticism with aggravating words. Peace negotiator During his time as congressman, Serpa was always assisting and representing the government in conflicts between worker unions, social conflicts