My paper proposal intends to show how the issue of “political charisma”, that is all too often dealt with in purely theoretical terms, could benefit from ethnographic fieldwork. After a hotly debated and contested failure to win the 2006 Mexican presidential election, Andrés Manuel Lopez Obrador, the PRD (Democratic Revolution Party) candidate, has himself “elected” as the “legitimate president” of the country by his unwavering supporters during a mass-meeting. He then sets up a shadow government cabinet made up of 12 ministers. During 3 years, AMLO (as he is usually called) tours intensively the countryside, stopping in each and every of the 2 500 districts of the country in order to convince his supporters to enroll as “delegates of the Legitimate Government”. He therefore succeeds in registering no less than 3 million people. Managed by way of sophisticated electronic devices so as to be put at the disposal of local district leaders showing sympathy for AMLO, this register of supporters becomes a powerful mobilization tool. What I wish to do in my paper is to understand how a political leader with strong political capital but uprooted from his own party, and therefore lacking in institutional resources, manages to survive an electoral defeat. Contrary to what many studies of Latin-American political parties postulate, AMLO’s “charisma” is not a given “once and for all” personal asset, but a contextual resource that needs to be constantly activated by way of a variety of devices. To describe these devices in their minute, routine details was the main aim of the fieldwork I led in Mexico in the past 5 years, both by touring lower-class districts with AMLO and by taking part in mass-rallies. The ethnographic data thus collected were supplemented by a quantitative survey led during mass-rallies and by 60 interviews with rank-and-file supporters and activists and 15 with high-ranking cadres.