LA PAZ - Bolivian President Evo Morales has called a referendum for December 7 to rewrite the constitution, sharpening a political struggle with rebel governors opposed to his sweeping socialist reforms.
"This is a historic day," he said late Thursday, announcing from his presidential palace in La Paz a decree setting up the plebiscite. "This is to deepen democracy."
The new referendum -- which had been widely expected since Morales won two-thirds support in an August 10 recall referendum confirming his mandate -- is "to consolidate the process of change," he said.
Regional authorities in the eastern state of Santa Cruz, an opposition bastion, immediately challenged the legality of the decree.
"We reject the policies that the government wants to impose through a decree," they said in a statement.
They stressed that the August 10 recall referendum had also solidly confirmed the mandates of several of the opposition governors ranged against Morales.
The rebel governors have already said they will not permit any such referendum to be held in their states.
The president, who became the first indigenous leader of Bolivia in 2006, is locked in a worsening power struggle with the governors of five of the country's nine states who are blocking his attempts to redistribute more land and national wealth to the indigenous majority.
The governors of the states of Santa Cruz, Beni, Tarija and Chuquisaca -- all with populations of mostly European descent and with indigenous minorities -- are demanding more control over revenues from gas fields in their territories that are vital to the economy of Bolivia, South America's poorest nation.
Morales has been prevented in recent weeks by protesters in those states from landing his aircraft. On Wednesday, he was forced to touch down over the border in Brazil after his helicopter ran low on fuel over opposition territory.
The long crisis had stymied Morales's forceful efforts to redraft the constitution to enshrine his reforms, and he had hoped the August 10 referendum would give him the upper hand.
Instead, the results secured his mandate and those of his chief foes. That briefly pushed them together for an attempt at dialogue to find a solution, but the talks failed.
The opposition governors quickly ratcheted up anti-Morales demonstrations, prompting the president last weekend to order troops to guard gas and oil installations in the east.
The threat of the confrontation turning into widespread unrest is real. A few violent incidents have already erupted over the past 18 months between pro- and anti-government protesters, resulting in half a dozen deaths.
Roads in some parts of eastern Bolivia are being blocked by anti-Morales protesters, and local authorities in those areas say they are "on a war-footing" against attempts to change the constitution.