Beni and Pando provinces hope to follow the lead of Santa Cruz
Two provinces in Bolivia are set to vote in a referendum on whether to declare autonomy from President Evo Morales's socialist government.
The votes on Sunday have been organised by conservative opponents in the lowland provinces of Beni and Pando.
They hope to follow the lead of the country's economic powerhouse, Santa Cruz, which voted for an autonomy package four weeks ago.
President Morales said the autonomy move was illegal.
Another autonomy vote is planned in Tarija, which has major gas reserves.
Analysts say the votes reflect the hostility of the country's business and landowning elite towards President Morales, and his policies aimed at transferring wealth to the poor indigenous people of the western Andean regions.
The president, who has more than two years left in office, faces a recall referendum on his leadership in August.
If successful in the ballot, Mr Morales says he wants to hold a public referendum on a draft constitution which has been awaiting approval since last year.
The constitution aims to enshrine reforms such as land redistribution to Bolivia's indigenous majority and sharing of wealth with the poorer western regions.
However, critics say it cedes too much control to the government in La Paz.
Mr Morales's opponents in the eastern states - home to a large part of Bolivia's oil and gas deposits - argue that his plans would unfairly privilege indigenous groups and would mean greater central control, including two consecutive five-year terms for the president.