Venezuela's united opposition voted Sunday in a first-ever primary which was expected to see youthful state governor Henrique Capriles chosen to challenge President Hugo Chavez in an October election.
Balloting closed at 2130 GMT at some 7,600 polling stations nationwide, after a one-hour extension. No incidents were reported in the voting.
Electoral commission president Teresa Albanes described turnout levels as "significant" and that results would be tallied during the night.
There was no official estimate of numbers of voters, but analysts said a turnout of around 10 percent of the 18 million eligible voters would be seen as a success.
Five candidates are running in the opposition contest led by Capriles, 39, the energetic governor of Miranda state and frontrunner, according to surveys.
"Let no one leave without voting," said Capriles after casting his ballot in the capital Caracas.
"We are expecting an extraordinary turnout."
The opposition is joining forces in an effort to defeat Chavez, a leftist firebrand ally of Cuba and harsh critic of the United States who has been criticized for jailing political opponents and restricting media opposition.
The 57-year-old Chavez, who last year underwent cancer surgery in Havana and now claims to be cancer-free, is seeking a third six-year term in the October 7 vote. But he faces challenges, from rising crime and corruption to the drop from record highs in oil prices, the country's main revenue source.
Capriles, telegenic and energetic, has been in politics since he was 25. His campaign got a boost last month when Leopoldo Lopez, a popular former mayor, dropped out and endorsed him.
He describes his politics as center-left, and has argued that Venezuela can "replicate" Brazil's model of economic development: allowing markets to play their role while also making social progress a priority.
His main rival in the ballot is Pablo Perez, 42, of the Un Nuevo Tiempo (A New Era) party. Perez governs Zulia, Venezuela's most populous and wealthiest state.
Both Perez and Capriles say they want to end the country's deep political polarization and have pledged to fight poverty.
They have campaigned with a conciliatory message and have avoided directly criticizing Chavez, the main political and economic ally of Cuba, the only one-party communist regime in the Americas.
They also propose continuing and improving the popular social programs adopted by the Chavez government since 2003, notably in health and housing.
The other candidates in the race are independent legislator Maria Corina Machado, labor leader Pablo Medina, and former ambassador Diego Arria. Unlike the governors, all three have chosen to aggressively challenge Chavez.
"This (vote) is not about changing the president. It is about changing a model that has failed," Capriles said on the campaign trail last week.
A lawyer with movie-star looks whose family includes Jewish immigrants, Capriles would seem to embody a generational change as well as a political one.
Capriles and Perez have emerged in recent months as favorites "precisely because they sought to depolarize the country and refrained from confronting Chavez," said historian Margarita Lopez Maya.
Many of those going to the polls welcome the opportunity.
"We want a change. I have always voted here against the government," said 35-year-old shopkeeper Alexis Mendoza.
"I'm voting for my country, for the future, for democracy and freedom," added 45-year-old bank employee Jose Luis Maldonado, who said he believed government officials were taking pictures of voters to try to intimidate them.
Ballots were also being cast Sunday in Venezuela's sizeable expatriate community in Florida, many of whom are eager to see change in their homeland.
"This is a process that reaffirms our commitment to democracy," said Pedro Mena, leader of a prominent opposition group in Miami.
A total of 20,000 Venezuelans living in the southeastern United States were eligible to vote. Officials put final turnout in Miami at 8,000.
In January, the opposition parties unveiled a unity platform focusing on free-market economics and emphasizing public safety.
The document calls for an end to price controls in place since 2003; adoption of a competitive currency exchange rate; reassessing Chavez's creation of a socialist state; and returning autonomy to the central bank.