Indigenous groups staged new protests and set up roadblocks Friday after President Carlos Mesa attempted to defuse weeks of unrest by announcing a constitutional assembly for later this year.

"Mesa go home, power for the people," thousands of Indians shouted as they marched through downtown La Paz in colorful ponchos and shawls, brandishing clubs and whips.

Late Thursday, Mesa signed a decree designating Oct. 16 as the date Bolivians will elect members of an assembly that is to rewrite the country's constitution with the aim of redistributing power in favor of the Indians, long ignored by the political system.

On the same day, he said, Bolivians will vote on increasing the provinces' autonomy from La Paz. The nationwide referendum is meant to head off a unilateral push for autonomy by the rich eastern provinces that hold most of Bolivia's gas and oil -- a demand that has incensed indigenous groups.

Mesa resorted to the move after Congress failed to reach a consensus for the third straight day while Indian protesters demanding nationalization of the gas industry brought the capital to a standstill.

A political independent with few friends in Congress, Mesa has faced considerable turmoil since he took over in October 2003 after an Indian revolt toppled his predecessor, Gonzalo Sanchez de Lozada, a Washington ally.

But experts and lawmakers questioned the legality of what may be his last card.

"This decree is unconstitutional," said lawyer Jose Luis Gutierrez Sardan. "It's a pity the two powers can't coordinate."

Congress is expected to review the decree in its next session on Tuesday, and Mesa appealed for lawmakers' support.

The streets of La Paz remained tense Friday, with many banks and other businesses boarding up windows and placing private security guards at the doors.

Mesa came to power promising to heal the social divisions of a poor country of 8.3 million people where Indians are in the majority. But he has not been able to control the growing political militancy of the Indian groups, visible both on the streets and in Congress.

Evo Morales, the main opposition and indigenous leader, called the decree "another show" by Mesa to demobilize the protests and said Congress could reject it.

Bolivian Indians march toward La Paz, the capital, after President Carlos Mesa set Oct. 16 as the date for the election of a constitutional assembly.