CARACAS, Venezuela — Venezuelan President Hugo Chavez has secured six more years in office after defeating his opponent in a closely watched presidential election that both candidates described as a historic vote.

Chavez, who has been president since 1999, overcame an energetic challenge from opposition candidate Henrique Capriles Radonski, according to results released late Sunday.

Fireworks peppered the sky over Caracas after the provisional results were announced.

“Today we have demonstrated — comrades, compatriots — that our democracy is one of the best in the world,” Chavez said in a speech from the balcony of the presidential palace to thousands of supporters who cheered and waved flags.

He thanked those who had voted for him and acknowledged those who had voted against him, applauding their “democratic attitude.”

With 90% of the ballots counted, Chavez had more than 54% of votes, with nearly 45% for Capriles, Venezuela’s National Electoral Council said Sunday night.

Chavez had secured 7.4 million votes and Capriles 6.1 million votes, election officials said. It was a significant showing — but not enough to win — for Capriles’ campaign, which had criticized the Chavez administration for inefficiencies, infrastructure shortcomings and corruption.

“We began the construction of a path,” the opposition coalition candidate told supporters after conceding his defeat. Capriles congratulated Chavez on his victory and urged him to take into account the different views expressed by voters.

“Being a good president means working for the vision of all Venezuelans,” he said.

Chavez has had more than a decade to implement his vision of 21st century socialism, a view that emphasizes the use of state oil windfalls to fund social programs. During his campaign, he highlighted his accomplishments in housing, education and health initiatives and acknowledged he needed to do more on crime and government bureaucracy.

The ebullient leader is 58 years old and has been visibly weakened by two surgeries for cancer. He has kept secret the kind of cancer he has and his prognosis.

His victory gives him “the opportunity to consolidate his policies” and also reaffirms the approach his government has taken to international relations, said Miguel Tinker Salas, a Latin American history professor at Pomona College in California.

Chavez’s influence over Latin America’s left-leaning governments has often rankled the United States, Venezuela’s largest trading partner. Venezuela is the fourth-largest exporter of oil to the United States.

Despite that tight economic relationship, the two countries are far from close allies: Chavez often rails against the United States and its allies as “imperialists” and has supported controversial world leaders like President Mahmoud Ahmadinejad of Iran.

The election result Sunday means the U.S. government will have to continue to deal with Chavez’s provocatively independent brand of diplomacy.

“I think Washington will have to start getting used to the fact that countries in Latin America, especially South America, are charting their own course,” said Tinker Salas.

Observers had said Capriles, 40, represented a moderate alternative to Chavez, the charismatic standard-bearer of the Latin American left. Capriles had vowed not to end the social programs that Chavez had set up, and he had promised to fight corruption that had grown in the public sector.

Capriles is a high-profile conservative who was a mayor, a parliament member and governor of Miranda, which adjoins the nation’s capital. The attorney-turned-politician had been so active on the campaign trial that he earned the nicknamed the “roadrunner.”

He appeared to have mounted one of the strongest challenges so far in Chavez’s 13 years in power. But his efforts ultimately proved insufficient to unseat the incumbent.

The opposition will now have to try to maintain a unified front for regional elections scheduled to take place in December, Tinker Salas said. That may prove difficult, he said, since “the one thing that brought them together was the figure of Chavez.”

The country saw one of its high participation rates in decades Sunday, with almost 81% of voters going to the polls, according to Tibisay Lucena, president of the National Electoral Council.

In fact, some polls were kept open two hours after their scheduled closing because of lines of voters waiting for ballots.

The army was deployed around the country throughout the day to ensure a peaceful and secure vote, said Maj. Gen. Wilmer Barrientos, commander of strategic operations command.

Nearly 140,000 troops were deployed throughout the country to guard polls and keep the peace, state-run VTV reported.

In a phone call aired on state-run television earlier in the evening, Chavez had asked people to remain calm until the election results were completed and for there to be no violence.

Long lines began forming early in the morning at polling stations from remote regions of the Amazon to the bustling capital of Caracas.

By mid-afternoon, Barrientos reported 15 electoral offenses throughout the entire country, the Venezuelan military said on its Twitter account. No further details were immediately available.

The election also drew voters from beyond the country’s borders as thousands of Venezuelans living abroad lined up to cast their ballots at diplomatic offices.

In New Orleans, Louisiana, voters streamed into the Venezuelan Consulate. Many traveled by bus from Miami, where Venezuelan authorities closed a consulate in January after the United States expelled the office’s top Venezuelan diplomat.

In Caracas, voters said they were happy to be casting their ballots.

“I’m really proud of the people, because everyone is cheerful about this event and I think there is a good feeling,” said Jesus Betancourt, a 25-year-old student.

Standing outside the Caracas school where Chavez cast his ballot, Katherene Rivas said she hoped Venezuelans would respect the results.

“For now, everything is quiet here, and we want that after the results are announced, that people remain calm,” she said.

— Journalist Osmary Hernandez and CNN’s Mariano Castillo, Paula Newton, Gustavo Valdes, Helena DeMoura, Patricia Janiot, Rafael Romo, Michael Martinez, Jethro Mullen and Richard Singer contributed to this report.