CARACAS -- In the predawn hours Sunday, fireworks will go off, trumpets will blare and Minerva Velitez will start knocking on neighbors’ doors, urging them to vote for Nicolás Maduro.

During his 14 years in office, late-President Hugo Chávez built a formidable logistics operation capable of mobilizing millions of the faithful. During critical campaign rallies, hundreds of packed buses, coordinated by people such as Velitez, can help swell the ranks. On Election Day, these same organizers will be the backbone of the government’s get-out-the-vote machine, which has rarely been defeated.

Polls give Maduro, 50, the interim-president and Chávez’s handpicked successor, a narrowing lead as he has vowed to carry on his boss’ social programs.

His rival, Henrique Capriles, 40, has been attracting massive crowds with his promises to bridge the political divide and invigorate the economy even as he keeps an eye on the country’s poor.

But both men know that enthusiasm alone won’t be enough to win Sunday’s race. And that’s where people like Velitez come in.

During the last presidential election in October, Velitez, 54, was one of more than 704,000 Chávez volunteers assigned to herd others to the polls. She was responsible for 20 voters and she said the ruling Unified Socialist Party of Venezuela, PSUV, had rented cars so she could hunt down stragglers.

“A couple of them got away,” she said. “But almost everyone on my list voted.”

The strategy, which the administration calls “one for 10” or “one for 20,” often generates a last-minute rush as laggards are brought in. And in October, it helped Chávez clench an 11-point lead over Capriles.

But the administration has other advantages. During the presidential vote and the December governors’ race — where Chávez allies won 20 out of 23 states — government vehicles, particularly those belonging to state oil company PDVSA, could be seen shuttling sympathizers to the polls.

“The reality is that we’re not facing Nicolás Maduro, but the entire state,” said Alejandro Vivas, the coordinator of Capriles’ get-out-the-vote effort. “The petrol-checkbook of PDVSA is at the service of their party.”

Vivas said that during the last two votes there was also evidence that the country’s 2.4 million public-sector workers, and hundreds of thousands of government welfare recipients, were being pressured to vote along party lines.

The opposition is pushing back. It has recruited 168,000 official movilizadores or “mobilizers” and 180,000 additional volunteers who will try to encourage people to head to the polls. Capriles backers are also being asked to stay until the votes are audited to keep the government honest. Using Twitter, social networks and TV spots, they’re hoping to make the get-out-the-vote campaign a viral citizens movement.

“This is an unfair and uphill battle,” Vivas said. “And the only way to make it work is if everyone is involved.”

Luís Lara, the director of the Venezuelan Election Observatory, an independent watchdog, said the “myth” of the PSUV’s get-out-the-vote machine may be exaggerated.

“At the end of the day, the vast majority of voters head to the polls on their own,” he said. And because the vote is secret, mobilization efforts can be a double-edged sword.