Nicaraguan President Daniel Ortega is set to secure a controversial third term with a landslide victory in the country's presidential election.
Mr Ortega won more than 60% of the vote, with his closest rival, Fabio Gadea, on 25%, early results showed.
Supporters of Mr Ortega's Sandinista Party celebrated, but the opposition said there had been electoral fraud.
Mr Ortega was allowed to run after the Sandinista-controlled Supreme Court overturned a ban on consecutive terms.
As vote-counting continued, Mr Ortega's supporters took to the streets of the capital, Managua, to celebrate.
"This is the victory of Christianity, socialism and solidarity," said Mr Ortega's wife and spokeswoman, Rosario Murillo.
But the opposition highlighted what it said was widespread manipulation of the vote by the president's party.
Liberal Independent Party (PLI) representatives said their parallel counting suggested an even race "before taking into account the rural vote", where they believe their candidate, Mr Gadea, will perform well.
Several independent electoral observers who were not accredited by the Nicaraguan authorities pointed to reports of fraud.
Official observers have so far not detailed any significant problems. The head of the mission from the Organisation of American States, Dante Caputo, said that his team had not seen "significant irregularities", but he called on the authorities to investigate all complaints.
The head of the European Union mission, Luis Yanez, said the polls had taken place "in a climate of normality and tranquillity".
Mr Yanez did, however, highlight what he called the "unusual way" in which Mr Ortega had been able to stand for a second consecutive term.
He was referring to a move by the Sandinista-controlled Supreme Court in 2009 which changed the rules of re-election allowing Mr Ortega to run despite a ban on back-to-back terms.
Daniel Ortega has been a leading figure in Nicaraguan politics since he led the Sandinista movement to overthrew dictator Anastasio Somoza in 1979.
He ruled Nicaragua for the next 11 years - fighting a civil war against the US-backed Contra rebels - before being voted out of power in 1990.
He failed in successive bids for re-election in 1996 and 2001, but in 2006 he was voted back into office thanks to a much softer image and a divided opposition.
His election opponents say Mr Ortega has only managed to finish the campaign ahead in the different opinion polls by intimidating his adversaries and abusing his office, the BBC's Arturo Wallace in Managua says.
Many Nicaraguans have benefited from the social programmes set up by Mr Ortega's government in the last five years with financial help from his ally, Venezuelan President Hugo Chavez.
Voters were also electing members of the National Assembly, with reports indicating that the Sandinistas (FSLN) were on course to win a majority.