(CNN) -- Left-leaning Nicaraguan President Daniel Ortega easily won re-election with more than double the votes of his closest rival, election officials said on Monday, amid complaints of voting irregularities.
With 85% of the ballots counted, the incumbent had 62.6% of the vote, versus Fabio Gadea's 30.9%.
"I want to congratulate the current president," Roberto Rivas, president of the Supreme Electoral Council (CSE), told reporters.
Opposition leaders have criticized Sunday's vote and Gadea, Ortega's closest rival, refused to accept the results.
He was known until recently as a radio-station owner and journalist and as creator of the popular Nicaraguan radio character "Pancho Madrigal."
"We can't accept the results presented by the CSE as they don't reflect the will of the people," Gadea said.
According to opposition leader Eliseo Nunez of the Liberal Independent Party, 20% of election observers had been stopped from entering polling stations.
"This has been a process plagued with irregularities," he said.
U.S. State Department spokeswoman Victoria Nuland similarly weighed in Monday on reports of procedural irregularities and voter intimidation.
"Frankly, if the Nicaraguan government had nothing to hide, it should have allowed a broad compliment of international monitors," she told reporters in Washington.
Placing third, with 6% of votes, was former President Arnoldo Aleman. He was convicted of corruption during his term and sentenced to 20 years in prison in 2003, but in a controversial 2009 decision, the nation's top court overturned the conviction.
Nicaragua's constitution bars presidents from being re-elected, but that did not stop Ortega from running in his sixth straight presidential race. Supporters of the president celebrated what was then his apparent re-election victory in the streets of the country's capital Sunday night.
He was first elected as president in 1984, and ran unsuccessfully in 1990, 1996 and 2001 before being elected again in 2006.
Ortega is known as an ally of Venezuelan President Hugo Chavez and was a public supporter of former Libyan leader Moammar Gadhafi during the Libyan uprising.
But recently he has reached for the middle, making overtures to the business class and promising to lure foreign investors into the country.
"Our government program is the one in practice now and the one we have to improve, strengthen (and) develop," Ortega said recently.
For his supporters, re-election guarantees that social and economic programs will continue. They want to see more investment in infrastructure and technology, and more public housing, projects often financed through Venezuela.
Ortega came to power as part of the Sandinista rebels who overthrew the Somoza dynasty in 1979. He represents the Sandinista National Liberation Front.
His detractors accuse Ortega of having too much influence over the Supreme Electoral Council and the Supreme Court of Justice, which allowed his candidacy.
Yet his popular support remains high, particularly among the country's youth.
"The level of support shows a bit of a new generation that does not know the experience of the past, of 30 years ago, of the war that happened in Nicaragua," said Manuel Orozco, a senior associate at the Washington-based Inter-American Dialogue.
CNN's Lucia Navarro and Jack Maddox contributed to this report.