LA PAZ, Bolivia (AP) — Cheered by thousands of supporters in Bolivia's coca-growing Chapare region, President Evo Morales began his campaign for his third consecutive re-election Saturday amid assertions by his opponents that the constitution prohibits him from running again.

Morales, a one-time leader of coca farmers, became the Andean nation's first indigenous president in January 2006 and is one of the few remaining leaders of the wave of leftists who swept into office in South America in past decades. If he is re-elected in October and serves out the five-year term, he would have been president for almost two decades.

Last year, Bolivia's top electoral court accepted Morales' candidacy despite a constitutional ban and a referendum in which 51% of Bolivians rejected his intention to modify the constitution to allow him to run again.