Bolivia's Congress voted Thursday to hold a nationwide referendum on a new constitution drafted by supporters of President Evo Morales.
The constitutional overhaul would grant greater political power to Bolivia's long-oppressed indigenous people who form the base of Morales' support.
Thursday's vote brings an end to two months of failed negotiations with opposition groups who refuse to recognize the proposed constitution. Opposition lawmakers walked out on the constitutional assembly last year.
Protesters blocked many opposition lawmakers from attending the session Thursday.
The referendum will be held May 4, the same day the eastern state of Santa Cruz, a Morales opposition stronghold, is scheduled to hold a vote on a proposal to declare autonomy.
Three other opposition-controlled eastern states, representing Bolivia's wealthiest provinces, are planning to cast votes on autonomy issues later this year.
Mr. Morales, Bolivia's first indigenous president, wants to break up the large land holdings of eastern farmers, many of whom are of European descent, and redistribute the property among indigenous groups.
He also wants to redistribute the nation's oil and gas wealth, which is centered in the east.
The four provinces are seeking to keep much of the tax revenues they generate. They say they do not want independence, but want to control their own wealth.
Some information for this report was provided by AP and Reuters.