A “Documento de trabajo número uno” (Working Paper Number One), dated October 1, 1986, was signed by a group of PRI members, among them Cuauhtémoc Cárdenas and Porfirio Muñoz Ledo. The group, known as the Corriente Democrática, asked the party to open the selection of its candidates to its base. It questioned the dedazo, the method by which the candidate for president was designated.
On March 4, 1987, at the party’s national assembly, PRI president Jorge de la Vega Domínguez said: “En el PRI no tendrán cabida ni la quinta columna ni los caballos de Troya” (In the PRI there will be no room for a fifth column or for Trojan horses). In October 1987, Cárdenas joined another party, the PARM, as its presidential candidate.
The objection was made in a signed document, inside the party. By the end of 1987, Cárdenas and Muñoz Ledo had both left the PRI.