Venezuela's government weighed a petition Tuesday for a nonbinding referendum on Hugo Chavez's presidency as opponents charged he had lost control of his government after a day of street riots.

"Is there a government in Venezuela? ... Who has the authority in Venezuela?" opposition lawmaker Gerardo Blyde asked during a congressional debate on Monday's violence.

At least 17 people were wounded by rubber bullets and more than 60 others hurt by rocks or felled by tear gas in the clashes between Chavez's supporters and police and National Guard troops in downtown Caracas.

The violence began after hundreds of Chavez's supporters tried to block opposition marchers from delivering more than 2 million signatures to the National Election Council demanding the referendum.

Election officials began verifying the signatures Tuesday — aware that any decision could spark more violence. Petitioners want a vote by Dec. 4, but officials said it would take a month to verify the signatures and weeks more to organize a vote.

Opponents have threatened a general strike if Chavez fights the vote. Chavez's supporters, on the other hand, have threatened more rioting if the council approves the signatures.

Carlos Ortega, head of the 1 million-member Venezuelan Workers Confederation, said Tuesday he was ready to call a general strike even before election officials make a decision.

Chavez says that according to the constitution a binding referendum can be called only halfway into his six-year term, or next August. He has said he welcomes such a vote, confident he can beat any challenger.

According to Venezuela's constitution, a nonbinding referendum on matters of national importance can be called with the support of 10 percent of the electorate, or 1.2 million people.

Chavez insists a nonbinding referendum cannot be used to ask about a president's term. But he has suggested that a change to the constitution could allow for a binding referendum before August.

Monday's rioting convulsed a nation that in the past month has seen two failed coup plots, a small military rebellion, two alleged assassination plots against Chavez and a one-day national strike.

Cesar Gaviria, secretary general of the Organization of American States, was in Caracas Tuesday to start negotiations and avert chaos in the fifth largest oil producer in the world and a major supplier to the United States.

On Tuesday, the government expelled from the military four of the 120 military officers who have occupied an eastern Caracas plaza for 14 days to demand Chavez's ouster. The officers were navy rear admiral Hector Ramirez Perez and navy vice admirals Daniel Comisso Urdaneta, Jose Noriega and Salvatore Scettro.

Government officials were apologetic over the rioting.

"The events were lamentable. They shouldn't have happened," said Foreign Minister Roy Chaderton. "But it happened and it can't be a reason not to talk. On the contrary, it's another reason for us reach an agreement."

Some analysts said the opposition could cite Monday's violence as an excuse to avoid negotiations and push for Chavez's ouster. Opponents can portray Chavez as "radical and authoritarian, and themselves as more democratic," said Luis Vicente Leon, director of the Datanalisis polling firm. "I think they'll use it as an excuse not to negotiate."