Some analysts say any opposition divisions to emerge after Capriles' loss would help Chavez's allies. So far, opposition leaders have maintained at least a public show of unity.
"Recrimination over their electoral defeat could produce fissures," said Miguel Tinker Salas, a Latin American studies professor at Pomona College in Claremont, California.
Divergences over political ideology could also fracture the opposition coalition, with some conservative parties that had lined up behind Capriles already complaining about his center-left stances.
"One of the main factors impeding unity is the lack of real consensus on an alternative proposal for the nation that can challenge the Chavez government," Tinker Salas said.
Despite the skepticism, Capriles dismissed suggestions that infighting could compromise the opposition's unity. The opposition held its first ever presidential primary in February and promptly closed ranks behind Capriles, the winner.
"Without a doubt, we have very big political capital that cannot be lost," Capriles said. "Our unity remains and our unity should be strengthened."
What will surely continue is the government machine built by Chavez that many say has won the president 14 years of loyalty. That includes at least 2.4 million national government employees, making up 8 percent of the country's population. By comparison, the United States, with tenfold the population, has almost the same number of federal employees, at 2.7 million.
Chavez ramped up public spending in the run-up to the election, building public housing and bankrolling social programs. Venezuela has the largest proven oil reserves in the world and received hundreds of billions of dollars in oil revenue over the past decade.
Retired electrician Manuel Millan said he could see the Chavez campaign all around him before the vote. Indeed, Chavez's image and slogans are everywhere in this country of 29 million people, from street posts to the uniforms of customs agents inspecting foreign visitors.
"The Chavez machinery was very big — vehicles, posters, TV broadcasts," Millan said. "The other candidate almost didn't have any of it."
Capriles complained that during the campaign the electoral council did nothing while Chavez regularly used his powers as president to take over the airwaves for appearances. "Why couldn't they have been regulated?" Capriles said.
For the moment, it appears Capriles will remain the opposition's top figure despite his loss.
He said he will be working hard as the gubernatorial elections approach, though he hasn't yet decided whether he will run for re-election in Miranda state, which includes part of Caracas. "I'm going to do everything in my reach for all the candidates for governor and mayor to win."
Despite Sunday's setback, many opposition supporters still see Capriles as the country's best bet for a brighter future — without Chavez.
As journalists mingled outside Capriles' campaign headquarters Monday, a young woman leaned out the window of a passing car and shouted: "I love you! Until the next one!"
Associated Press writers Jorge Rueda, Ian James, Fabiola Sanchez and Vivian Sequera contributed to this report.
Christopher Toothaker on Twitter: http://twitter.com/ctoothaker