But the former army paratrooper, who celebrated his 57th birthday Thursday from the balcony of the presidential palace, has been visibly weakened by two operations in Havana and his first chemotherapy session since announcing last month that he has cancer. And after years of setbacks, his political adversaries sense that in next year’s presidential election, they might be in a position to get the upper hand against a leader who has dominated this country for a dozen years.

In a poll released last week by the Caracas firm Datanalisis, the governor of the centrally located state of Miranda, Henrique Capriles, nearly tied Chavez, 37 percent to 39 percent, when prospective voters were asked which of the two they would choose.

Capriles is using his position, and the coffers he controls as governor, to his advantage, surging ahead of others in Venezuela’s often-fractious opposition movement who want to challenge Chavez.

The telegenic 39-year-old hammers away at the government’s inability to control rampant crime and inflation, as well as what he calls the mismanagement of an economy that has been South America’s laggard despite its huge oil reserves.

But it is in campaign swings through poor districts, such as largely rural Las Mercedes in the mountains south of Caracas, where Capriles’s message has had particular resonance. Wearing a white tennis shirt and baseball cap on a recent day, he arrived by helicopter at a ballfield, where he was immediately swamped by poor villagers.

Some asked about jobs. Others wanted help with home repairs. He spoke to as many as he could before leading a pack of supporters and aides, clipboards in hand, on a sprint along rutted, unpaved roads dotted with cinder-block homes, the pastel-colored walls fading in the tropical sun.

“If we can resolve these cases, and then get to others, we’ll resolve them,” he said in his gravelly voice, as a mob of residents surrounded him.

Handing out vouchers for residents here to renovate their homes quickly won him points from Julia Pacheco, 35, who received a hug from Capriles in her living room.

“Very excellent, marvelous. He’s very good, Governor Capriles,” Pacheco said, as she held up a voucher he had given her.

Another homeowner, Alfredo Ascanio, 54, said Caprile’s message was “admirable, admirable; this is what we need, a president who looks after the people, not just himself.”

A ‘new Chavez’

In an interview, Capriles said government interventions in the economy, especially the Chavez administration’s seizure of land and nationalization of companies, have hobbled Venezuela. He also talked about the need for business-friendly policies to generate jobs. His model for Venezuela is Miranda, where his governorship has been popular.

“In Miranda, we do not promise, we do,” said Capriles, who tries to stress the technocratic merits of his candidacy. “We can show results in education, in health, in home construction. We have a vision of what employment should be.”

Still, there is another side to Capriles, political analysts say, one not all that dissimilar from Chavez. Capriles has a gift for rhetorical flourishes and a penchant for relying on handouts to connect with voters.

“The only doubt I have about him is that he sometimes likes to be a ‘new Chavez,’ but from the opposition,” said Carlos Romero, a lecturer and a political scientist at the Central University of Venezuela. “The only way to win the election is to present himself as different from Chavez, as a leader who is committed to democracy, as a leader who is serious, as a leader who is not a demagogue, as a leader who is not a populist.”

Chavez, to be sure, remains Venezuela’s most influential and popular politician.

Last week’s Datanalisis poll, for instance, showed that Chavez’s approval rating remained at 50 percent. The poll’s director, Luis Vicente Leon, said respondents still choose Chavez when they are presented with a scenario in which the president faces a group of leading opponents.

“Chavez is the president, everybody knows him,” Leon said. “He has the money, he has the political party, he has the Internet, he has the media control, he has everything.”

The question, though, is whether Chavez will make a full recovery in the months ahead of the December 2012 vote.

In an interview published Monday in the state newspaper Correo del Orinoco, Chavez said he was “resolved to reach 2031” in power, which would mean three more six-year terms.

“On a personal level,” he told the newspaper, “I tell you I have never thought for even an instant of retiring from the presidency.”

A flurry of activity

In a flurry of activity this week, Chavez sought to demonstrate that he was still in command, even of the minor details of governing.

He announced Venezuelan famine relief for Somalia, said the state oil company would ramp up production, and oversaw meetings with his top aides. He also appeared as feisty as ever, mocking the Obama administration over the debt crisis and using his favorite put-down to describe his foes, calling them “squalid ones.”

He even took time out to tell state television in a phone call that Simon Bolivar, the country’s liberator and the president’s guiding light, had been murdered in 1830, though a year-long scientific study of his remains came up with no evidence of foul play.

While Chavez has yet to reveal what kind of cancer he has, he told Venezuelans this week that he would undergo a second and third phase of chemotherapy. Speaking to state television this week, he discussed the side effects.

“Surely within not many days, you will see a bald Chavez,” the president said. “Do you remember Yul Brynner? I’ll be a bit like Yul Chavez. My hair is going to start to fall out.”