The 36-year-old economist, a protege of former President Rafael Correa, ran on promises to make $US1 billion ($A1.3 billion) in direct payments to families and disavow the conditions of a $US6.5 billion IMF financing package.

His main rival, Guillermo Lasso, has promised more foreign investment and increased oil production but has been hurt by his image as a conservative banker.

Lawyer and indigenous activist Yaku Perez ran on an anti-mining platform.

"The victory, as we have said, is big. It's a ratio of 2-to-1 against the banker candidate who appears to be in second place," Arauz told a news conference on Sunday.

"We have to see the final results, but we are very happy."

An exit poll by local pollster Clima Social showed Arauz with 36.2 per cent of the vote compared with 21.7 per cent for Lasso and 16.7 per cent for Perez.

A second poll by Cedatos showed Arauz with 34.9 per cent of the vote compared with 21 per cent for Lasso and 18 per cent for Perez.

To win in a single round, Arauz needs more than 50 per cent of valid votes, or 40 per cent total with 10 percentage points more than the runner-up.

Arauz did not say if he had enough votes to avoid a run-off.

The elections council was expected to release an official quick count between 7 pm and 8 pm local time.

A brutal coronavirus outbreak last year left bodies uncollected on the streets of Ecuador's largest city, Guayaquil.

Lockdowns around the world slashed fuel demand and prices for oil, Ecuador's main export, battering an economy also reeling from sharp cuts to government spending.

President Lenin Moreno, a former Correa ally, drove a pro-market agenda in hopes of reviving a sluggish and heavily indebted economy.

His efforts sparked an angry backlash, with 10 days of violent street protests in 2019 against a planned fuel price hike.

Moreno, who took office in 2017, did not seek a second term.

Australian Associated Press