Left wing nationalist Rafael Correa has claimed victory in the country's presidential election.
With about 21 per cent of the ballot counted, Mr Correa had 65 per cent compared to 35 per cent for Alvaro Noboa, according to Ecuador's Supreme Electoral Tribunal.
The results were consistent with an unofficial count by an election watchdog group and two exit polls.
Mr Correa, a US-trained economist who has rattled Wall Street, has promised radical change
by threatening to reduce foreign debt payments and oppose a free trade arrangement with the United States.
His election would strengthen South America's tilt to the left, with Ecuador joining like-minded governments in Venezuela, Bolivia and several other countries.
"We receive this very high honour that the Ecuadorean people have bestowed on us with profound serenity, with profound hope," Mr Correa told a news conference.
But his opponent, Alvaro Noboa, declined to concede defeat, saying he would wait for the official count to be finished.
Mr Correa (43), who is an admirer of Venezuela's President Hugo Chavez, secured a place in yesterday's runoff by pledging a "citizens' revolution" to radically reform the discredited political system.
Ecuadoreans have driven the last three elected presidents from power, and Mr Correa appealed to voters as a fresh face in a field of established politicians.
In the first round, Correa called President Bush "dimwitted" and threatened to reduce payments on Ecuador's $16.1 billion foreign debt to free up money for social programmes. He was favoured to win the first round but came in second to Noboa in the field of 13.