A poll released on Saturday showed Rafaefl Correa, a 43-year-old left-wing economist, to be virtually tied with Alvaro Noboa, a banana magnate, before voting begins for the presidential election on Sunday.
The survey showed Correa with 28.4 per cent of the vote and Noboa, 56 and Ecuador’s richest person, with 27 per cent.
Correa has maintained a strong lead in polls for several weeks and on Saturday alleged fraud in preparation for the vote.
He asked that Rafael Bielsa, the head of the Organization of American States observation team, should removed from his post for being biased.
Correa has promised to call a
vote to rewrite the constitution
Bielsa, an Argentine ex-foreign minister, said he would stay in Ecuador and that none of the charges of potential fraud had been proven.
In a crowded field of candidates neither Correa nor Noboa are expected to win the mandatory 40 per cent of votes for an outright victory, leading many to expect a run-off vote on November 26.
More than nine million Ecuadoreans will vote in the ballot, but the allegations of a fraud are the latest mark on a campaign characterized by voter apathy, with many of the public perceiving politicians as corrupt and inefficient.
One survey showed that nearly 30 per cent of voters were still undecided a week before the polls in a country where voting is madatory and political turmoil is common.
Three presidents have been toppled by civil unrest or congressional infighting in the last 10 years alone.
Correa has tried to benefit from voters' disillusionment with traditional parties who have failed to fight poverty and curb graft.
He has promised to call a popular vote to rewrite the constitution and strengthen the president's powers. He has pledged to suspend free trade talks with the US and is a supporter of Hugo Chavez, the Venezuelan president.
Noboa has sought to attract votes with promises of cheaper credit and housing for the poor.
Noboa is Ecuador's richest man
He is openly pro-US and says he is a market-friendly candidate who wants to sign a free trade deal and bolster investment.
Portraying himself as anti-communist he has often sounded more like a preacher than a politician and in one campaign rally said he should become president "because God has told me to become president."