He has rallied Bolivia's coca farmers against U.S.-led eradication efforts and helped lead anti-government protests by indigenous groups that have unseated two presidents in two years.
But opposition leader Evo Morales is now closing in on the office he has helped force others to flee.
Opinion polls show the leftist congressman holding a narrow lead in an upcoming presidential election. Scheduled for Dec 4, the election could be delayed due to political bickering over Congressional seats.
If elected, Morales would be Bolivia's first Indian president and add South America's poorest country to a regional political shift leftward that has seen leftist leaders rise to power in Argentina, Brazil, Chile, Uruguay and Venezuela.