BUENOS AIRES, Argentina (AP) _ Fernando De la Rua, the opposition leader who cast himself as the best bet for a populace weary of recession and the flamboyant decade-long rule of Carlos Menem, appeared headed for a landslide victory in Sunday's presidential vote, exit polls showed.

De la Rua, the 62-year-old mayor of Buenos Aires, scored just over 51 percent of the ballot to 35 percent for Eduardo Duhalde, 58, the candidate of Menem's Peronist Party and governor of Buenos Aires province, according to the exit poll broadcast by Radio Continential. The result was released moments after the balloting ended at 6 p.m. local time (5 p.m. EDT).

Should the official results uphold the figures, De la Rua would become president on Dec. 10.

Horn honking erupted in Buenos Aires as De la Rua supporters toasted the results of the exit poll, one of two showing a similar big victory for the Buenos Aires mayor. De la Rua himself had expressed confidence throughout the day.

``We did our campaign job,'' he said while casting his vote Sunday.

Menem, who voted in his native La Rioja Province, had scoffed at campaign polls suggesting his ruling Peronist party was headed for a resounding defeat in the presidential ballot.

``If I had been permitted to run, I am sure I would have won. But I still have time for a future presidential election,'' said Menem before flying back to the capital Sunday.

Menem had flirted with seeking an unprecedented third straight term, but was barred by a constitutional prohibition and has said he will run again in 2003.