Santiago Peña of Paraguay’s ruling conservative Colorado Party has won the presidential election, beating a centre-left challenger.
With almost all ballots counted, Mr Peña, an economist, got more than 42%, electoral officials say.
Efraín Alegre, candidate of the Concertación Nacional coalition, had nearly 28%. He later admitted defeat.
Sunday’s presidential poll was decided in a single round of voting.
Addressing his supporters, Mr Peña, 44, said: “Thank you for this Colorado victory, thank you for this Paraguayan victory.”
He also called for nationwide unity and consensus. Paraguay’s economy is expected to grow by more than 4% this year, but the country has relatively high levels of poverty and corruption.
“We have a lot to do, after the last years of economic stagnation, of fiscal deficit, the task that awaits us is not for a single person or for a party,” Mr Peña said.
Meanwhile, Mr Alegre, 60, said his coalition had made significant efforts but the election results showed this was not enough.
During his campaigning, he advocated austerity measures to combat the growing fiscal deficit and pledged to tackle corruption.
He also proposed dropping his country’s long-running ties with Taiwan and instead aligning with China.
Paraguay is currently among only 14 countries who have official diplomatic relations with Taiwan.
China regards the island as a renegade province, which should be returned – including by force if needed – to Beijing’s control.