During the Presidency of Carlos Lleras Restrepo, he was Minister of Government 1966-1968, led in Congress a constitutional reform and was Colombian ambassador in Washington from 1968-1969, when he returned to campaign for the Presidency.
Under president Carlos Lleras Restrepo var han inrikesminister 1966-1968, ledde i kongressen en konstitutionell reform och var Colombias ambassadör i Washington, D.C. 1968-1969, då han återvände till kampanj för presidentvalet.