Four Bolivian provinces have announced their intention to create their own independent regional governments.
Santa Cruz, Tarija, Beni and Pando are scheduled to make formal autonomy announcements on Saturday.
Authorities have sent a 400 police officers to Santa Cruz to ensure security during the challenge to the Bolivian government.
The provinces object to President Evo Morales' moves to overhaul the constitution to boost presidential powers and increase the rights of Bolivia's indigenous majority.
Mr. Morales is the country's first indigenous president.
Some information for this report was provided by AFP and AP.