(Advisory to clients: Ecuadorean laws prohibit the publishing of polls in the country 10 days before the election)
By Alexandra Ulmer and Yury Garcia
QUITO/GUAYAQUIL, Feb 19 (Reuters) - Ecuadoreans vote on Sunday in a nail biter presidential election where an ally of leftist President Rafael Correa hopes to clinch enough support to avoid a runoff against a conservative ex-banker.
Lenin Moreno, 63, a disabled former vice-president, needs 40 percent of valid votes and a 10 percentage point difference with his nearest rival to avoid a second round on April 2 and continue a decade of left-wing rule in the Andean country.
He looked close in an early February poll, with an estimated 38.6 percent of valid votes versus 25.7 percent for his nearest challenger Guillermo Lasso, a 61-year-old former president of Banco de Guayaquil, according to top pollster Cedatos.
But should Moreno be forced into a second round, analysts expect Ecuador's fractured opposition to coalesce around Lasso amid an economic downturn and corruption scandals in OPEC's smallest member state.
That would further bolster the right in South America, after Argentina, Brazil and Peru all shifted away from leftist rule in the past 18 months as a commodities boom ended.
Still, Ecuador's ruling Country Alliance party remains popular with many poor in the country that is home to volcano-topped Andean plateaus, lush jungles and the Galapagos Islands.
"This government must continue because it's the best one in all political history. It's built everything: Hospitals, roads, schools," said student Cristopher Gonzalez, 26.
"I don't believe any candidate but Lenin Moreno."
Moreno, who lost use of his legs two decades ago after being shot during a robbery, has a more conciliatory style than the fiery Correa and has promised benefits for the disabled, single mothers, and the elderly.
But the economy is weighing heavily on voters.
Unemployment is running high, the middle class is upset over tax hikes, and corruption scandals at state-run oil company PetroEcuador and Brazilian conglomerate Odebrecht have outraged many.
"We've lived 10 years of disgrace, 10 years of theft, corruption, false honesty, a country-wide regression where only a few have benefited," said Angel Mendoza, a 45-year-old architect who was supporting Lasso.
Lasso has campaigned on a platform to revive the economy, which is dependent on exports of oil, flowers, and shrimp, by slashing taxes, fostering foreign investment, and creating 1 million jobs in four years.
He has also vowed a clean break with Correa's foreign policy. He would remove Wikileaks founder Julian Assange from the country's embassy in London by late June and take a firm stance against Venezuela's socialist government.
Analysts caution there is still a high number of undecided voters and the fact there are eight candidates in the first round render predictions tricky.
While some voters are disappointed by Correa's governance, they cannot bring themselves to vote for a former banker seen as out of touch with most Ecuadoreans' reality. And another opposition candidate, lawyer and former lawmaker Cynthia Viteri, is seen cutting into Lasso's support.
"It's hard to choose, their proposals are weak," said street seller Justo Aguilera, 46 in the humid coastal city of Guayaquil. "Because they're always fighting, they're not speaking about the economic crisis and we unemployed folk who have to work informally every day to at least eat."
The next president will face an uphill battle to create jobs, reckon with high debt levels, and maintain major social welfare plans amid lower crude prices.
Correa, one of the key figures of Latin America's leftist axis for years, has brought stability to the politically turbulent country but has aggravated many with his confrontational style. He plans to move to Belgium with his Belgian wife after leaving office.
Voters will also be asked to chose 137 members of the National Assembly, where no party is expected to clinch a majority, and vote on a proposed ban on public officials having accounts or assets in tax havens.
The next presidential term starts on May 24 and lasts four years. Polls close at 5 p.m. local time (2200 GMT) and preliminary results are expected to trickle in throughout the evening.
Additional reporting by Alexandra Valencia; Writing by Alexandra Ulmer