The Venezuelan capital of Caracas is gripped with violence and President Hugo Chavez has barricaded himself in the presidential palace surrounded by at least 1,000 soldiers who are loyal to him. At least twelve people have died and more than 90 have been injured in violent clashes between Chavez opponents and soldiers. A group of high-ranking military officers has called for the ouster of Mr. Chavez.

The man who came to fame in Venezuela by leading a failed military coup in 1992 may now face a similar attempt to remove him from power. Ten high-ranking officers from separate branches of the Venezuelan armed forces have announced that they no longer recognize the authority of Mr. Chavez. They accuse him of defiling the honor of the military by having snipers shoot at protesters. They are calling on other military officers to join them.

But inside the Miraflores palace, President Chavez remains defiant. He accuses opponents of using the news media to incite rebellion and foment violence and he ordered that all private television transmissions be cut. Mr. Chavez says he is no danger of being removed from office because the military and the people support him.

But observers in Caracas and in other parts of the region say the controversial left-leaning leader is facing his darkest hour. Much will depend on what the military does in the hours ahead.

President Chavez came to power with overwhelming electoral support three years ago, but in the past year or so he has seen his support steadily diminish. In an unusual turn of events for a Latin American nation, opposition to the president has grown to include groups normally opposed to each other. In recent months, business leaders and labor union representatives have marched side by side to call for Mr. Chavez to step down.

In recent days, striking oil workers have disrupted petroleum shipments and a nationwide strike has closed down all but a few businesses. Venezuela is the largest single supplier of oil to the United States and the fourth largest producer in the world.

The government relies on revenues from the state-owned industry for about half its funding. If the confrontation in Caracas is not resolved soon, industry analysts say it could cause a further increase in the price of oil on the world market.