CARACAS, VENEZUELA - Weakened from battling cancer, President Hugo Chavez is fighting for his political life as he faces a presidential election Sunday against a charismatic challenger who has energized a once disunited opposition in a way none of the populist leader's foes ever has.

At stake is the president's experiment to remake Venezuela, a 14-year transformation characterized by the expropriation of private companies, diplomatic initiatives to counter U.S. influence and a near-mystical bond with the country's poor masses.

Two established pollsters show Chavez, 58, with a substantial advantage, underscoring the loyalty of millions he has commanded since sweeping into power in 1998. But two others have Chavez and the challenger, Henrique Capriles, 40, a lawyer and former governor who has never lost an election, in a virtual dead heat.

"This is seriously competitive," said Cynthia Arnson, director of the Americas program at the Woodrow Wilson Center in Washington. "I would say it's the first time since Chavez was elected that the accumulated learning experience of the opposition and the accumulated problems of the country have brought the race to a place where it's almost too close to call."

The election is almost certainly being watched closely by Iran, which has found an ally in Venezuela, and myriad small countries in Latin America that have received aid in return for support against Washington.

The outcome is also expected to be tracked by energy markets. Venezuela recently surpassed Saudi Arabia as the country with the biggest certified oil reserves, and Chavez is considered a price hawk within the Organization of the Petroleum Exporting Countries, or OPEC, an organization Venezuela helped found.

Capriles campaign officials said they believe that the large number of undecided voters in some polls will break for the challenger at the ballot box, leading to Chavez's defeat. It is a bold prediction that is buttressed by the opposition's recent revival after years of uninspired campaigning and the disenchantment many Venezuelans express about decaying infrastructure, rampant crime and shoddy services.

But the president's advantage is undeniable. A state media apparatus has provided fawning coverage of the campaign, and his administration has provided prospective voters with gifts ranging from refrigerators to new apartments.

"He has given love and made it easy for the people, the only president we have had who has had anything to do with the poor," said Solea Arcila, a nurse. "Chavez will be here forever."

Still, there are signs that things are not as rosy for Chavez as they have been in the past. Analysts say Chavez's campaign has been lackluster, and nagging questions remain about his health, which is a state secret. That has many Venezuelans wondering whether the dashing former army paratrooper who stormed to prominence a generation ago as the leader of a failed coup has mustered the emotional appeal needed to get millions of voters to once more cast ballots for him.