Fernando Llano, Associated Press
Venezuela's President Hugo Chavez greets supporters during his caravan from Miraflores presidential palace to the airport in Caracas, Venezuela, Friday Feb. 24, 2012. Chavez bid an emotional goodbye to soldiers and supporters and waved to crowded streets in Caracas on his way to Cuba for urgent surgery to remove a tumor he says is probably malignant. The sign shows an image of Jesus Christ.

CARACAS, Venezuela — Amid a blackout on official information about Hugo Chavez's planned tumor operation in Cuba, Venezuelans on both sides of the political divide waited anxiously on Monday for news on the president's health.

Chavez, 57, was scheduled to undergo tests over the weekend and then be operated on early this week, but both Venezuelan and Cuban authorities were silent.

Cesar Urbaneja, a 58-year-old street vendor hawking posters of Chavez on a street corner in downtown Caracas, expressed concern.

"I'm worried about the health of my president, but I have faith in God ... that he'll come out of this," Urbaneja said.

Uncertainty has grown steadily since Chavez's last public comments, which came in a phone call late Friday to Venezuelan state television. Speaking shortly after arriving in Havana, he tried to reassure supporters that he would recover from surgery and soon return to Venezuela.

Urbaneja said he was fretting over the possibility that doctors might find the president's new tumor to be malignant, meaning the president would have to undergo another long round of chemotherapy as he did after Cuban surgeons removed a baseball-size tumor last June.

That could give the opposition's presidential candidate, Henrique Capriles, a better opportunity to win Venezuela's Oct. 7 presidential election, he said.

Urbaneja warned an opposition triumph in October would set Venezuela back and breed "poverty and more insecurity."

Without fresh information regarding Chavez's health, Venezuelan newspapers published editorials mostly focusing on his illness and its potential consequences as the country gears up for what is shaping up to be a tight presidential race.

Vice President Elias Jaua and Jorge Rodriguez, Chavez's chief campaign organizer, both spoke at length during public events Monday. But neither provided any news about the president's medical condition.

When Chavez was diagnosed with cancer and had surgery last year, Venezuelans learned about it after the fact via a brief announcement by Foreign Minister Nicolas Maduro.

Chavez was out of sight from early June until the end of that month, when he spoke from Havana about his operation.

Many observers expected Chavez's latest surgery to be done at Havana's Cimeq research hospital, and security outside the facility was low Monday, a possible indication that he was not yet there.

Traffic flowed freely in the streets around the hospital, and a waiting room was filled with Cubans who had regular appointments. The only sign of any stepped-up precautions was that guards asked visitors to give their names and license numbers before leaving their vehicles in a hospital parking lot, a measure in effect for more than a week.

Cuban and Venezuelan officials did not say where the operation would take place, but an obvious choice was Cimeq, a Spanish-language acronym for Center for Medical Surgical Investigations. Opened in 1982 to care for officials in Cuba's Interior Ministry and state security service, the hospital has treated a number of foreign dignitaries, including Bolivian President Evo Morales and Nicaraguan leader Daniel Ortega.

Cimeq doctors would likely care for Chavez in a highly exclusive section usually reserved for high-ranking Cuban government and military officials. Fidel Castro presumably was treated there for the grave intestinal illness that forced him from Cuba's presidency in 2006. That part of the hospital is closed to the public.

Maritza Monsalve, a fervent Chavez supporter, said she worried about Chavez and had appealed for divine intervention.

"What can one do? One must go on with their normal routine," said Monsalve, a 69-year-old housewife. "I cannot spend all day and all night thinking about what's happened to the president."

"God willing, he will be well," she added.

Some of the president's opponents were thinking about what might happen if Chavez was forced out of the picture.

Melvin Luengo, a 52-year-old shopkeeper, predicted that top-ranking members of Chavez's ruling party would be hard pressed to find a candidate capable of winning October's election if Chavez had to retire due to deteriorating health or even died of cancer.

"There's nobody with half the charisma Chavez has," Luengo said. "Unfortunately for them, Chavez didn't allow the emergence of leadership other than his own."

Associated Press writers Peter Orsi in Caracas and Anne-Marie Garcia in Havana contributed to this report.