QUITO, Ecuador (AP) _ The Harvard-educated mayor of Ecuador's capital failed to win a majority in presidential elections Sunday, forcing a runoff against a candidate favored by a disgraced former president, according to an exit poll.

Quito Mayor Jamil Mahuad received 36.7 percent of ballots cast by Ecuadoreans, who were hoping to elect a president who will end years of political and economic instability. Official results were expected Monday.

Business magnate Alvaro Noboa, a stand-in for ousted President Abdala Bucaram, received 29.8 percent of the votes, according to the poll, which was sponsored by seven television stations. In past elections the poll has proved highly accurate.

Overshadowing the voting was Bucaram, a fiery, charismatic populist who was forced from office in disgrace in February 1997 after six turbulent months in office. Since his ouster, the country has been run by interim President Fabian Alarcon.

Alarcon was appointed by Congress after legislators deposed Bucaram for ``mental incapacity.''

Noboa had surged into second place in public opinion polls in the final weeks of the campaign, and many Ecuadoreans worry that if Noboa wins in the second round, he will allow Bucaram _ known as ``El Loco'' (The Crazy One) _ to return to Ecuador from exile in Panama.

``Bucaram's phantom is hovering over the campaign,'' the Quito newspaper Hoy said last week.

Mahuad, a 48-year-old centrist, holds a master's degree in public administration from Harvard University and is boosted by his reputation as an effective, honest mayor _ a strong selling point in a country rife with corruption. He has pledged to improve health services and education and to combat rising crime.

``He's honest and prepared for the job,'' said Yolanda Vallejo, a 21-year-old office receptionist, as she stood in line to vote at a school in a middle-class Quito neighborhood. ``He's done a lot of good things for Quito and he can do the same for the country.''

The runoff vote was scheduled for July 12, with the winner taking office Aug. 10.

Because of voter disgust with Ecuador's corrupt and ineffective governments, turnout was not expected to surpass 60 percent. Ecuadoreans are skeptical of campaign pledges after repeated broken promises by political leaders since democracy was restored in 1979, the end of a decade of military and civilian dictatorships.

Despite his wealth, the 47-year-old Noboa is running with the backing of Bucaram's Roldosista party, which dubs itself ``the force of the poor.'' Borrowing from Bucaram's populist style, he has promised to create 1 million jobs and build 200,000 homes for the poor.

Bucaram, who like Noboa is from the booming Pacific port of Guayaquil, is being tried in absentia in three corruption cases, but he has sworn to return to politics in Ecuador. His party's TV ads show mobs of people in the streets with a voice in the background shouting ``People's Revenge.''

Mahuad voted early Sunday and said afterward that Ecuador desperately needed to regain trust at home and abroad.

``What's at stake in this election?'' he said. ``Choosing a person who guarantees Ecuador a stable, serious government that will ... generate jobs and bring international respect to Ecuador.''