|Lugo says 'a new chapter in our nation's political history' has been written [AFP]|
Election officials said that the tally accounted for nearly 1.7 million votes.
Ovelar conceded that Lugo, a 56-year-old former Roman Catholic bishop, had built an unassailable lead and that the outcome of Sunday's election was now "irreversible".
Ovelar, who would become Paraguay's first female president if she came out on top, had pledged to steer the ruling party in a new direction, to the benefit of all in the country.
The former education minister and protege of Nicanor Duarte, the outgoing president, had promised to lead the nation to "unprecedented economic growth".
Lugo's victory ends more than six decades of domination by the Colorado Party.
"Today we can affirm that the little ones can also win," he said.
Full results could take up to two weeks to be announced but firecrackers resounded in the capital Asuncion and cars clogged streets and honked their horns to celebrate what looked like Lugo's imminent victory.
|Ovelar conceded that Lugo had built |
an unassailable lead [Reuters]
Thousands of Lugo supporters rallied in a central square.
A nun who supported Lugo said: "We are confident he will govern with hand of God. He represents hope ... something new for our country."
Another Lugo supporter, Alberto Fernandez, a butcher, had gone to the polls not convinced his vote would be respected, but was sure about what he wanted.
"Many things ... jobs, health, education ... not for me but for the future of my three children," he said.
Before voting began, Lugo had said that his coalition appealed to Paraguayans from across the political spectrum.
"The Patriotic Front for Change consists of about 20 Indian, peasant and union organisations - from leftist groups to the conservative Radical Authentic party, Paraguay's largest opposition group.
Paraguay has gradually implemented democratic policies since Alfredo Stroessner, an anti-communist general, was removed from power in 1989.
Still, economic and social problems abound.
More than a quarter of Paraguayans have been forced to emigrate to feed their families.
Ninety percent of the nation's land is owned by less than two percent of the population, and about 40 per cent of people live in poverty.
Drug trafficking, crime and black marketeering are rampant.
Lugo has promised to implement policies designed to improve the lives of ordinary Paraguayans, causing big landowners to be concerned.
"We have 300,000 families without land and they have the constitutional right to own the soil they live on," Lugo has been quoted as saying.
Al Jazeera's Lucia Newman, reporting from Asuncion, said the real hard work will begin after the celebrations.
"This is not just about having a new president," she said.
"It is about changing the political culture of a country that has been characterised by corruption and authoritarian rule for more than six decades."
Source: Al Jazeera and agencies