By Daniel Ramos
LA PAZ, Oct 20 (Reuters) - Bolivians will vote in an election on Sunday to decide whether to extend the rule of President Evo Morales to nearly two decades or oust the great survivor of South America's "pink tide" of leftist leaders.
Morales, widely known as just "Evo," is the favorite to win, but it is set to be his toughest race yet since sweeping to power as Bolivia's first indigenous president in 2006. Recent opinion polls show he could win with his weakest ever mandate and may face a risky second round run-off.
In his favor, Morales - a former union leader for coca growers - has overseen a long stretch of political and economic stability for Bolivia, a landlocked country of 11 million people that is the continent's poorest. But support for him has slipped amid slowing economic growth and concerns about government corruption and anti-democratic practices.
"I support Evo because I want a stable economy," said Elsa Lima, 55, who sells sweets from a kiosk in the capital La Paz. "Otherwise everything will spin out of control and there will be crisis."
Others worry about his extended stay in power. Morales is running in defiance of term limits and despite a 2016 referendum in which Bolivians voted against him being allowed to seek a fourth consecutive term. A local court ruled in his favor to allow him to run anyway. As he did in the 2014 election, he has promised to retire after the five-year term is over.
Morales needs 40% of ballots and a 10-point lead to win outright on Sunday. Polls open at 8am (1200 GMT) and close eight hours later. The next president will govern from 2020-2025.
Despite growing disenchantment with Morales, support for the opposition will be divided among eight candidates, all of whom trail him by double digits in a recent poll by Viaciencia.
The leading opposition candidate, Carlos Mesa, a former president who resigned in 2005, has campaigned on a platform of saving Bolivia's democracy from Morales, whom he has portrayed as a power-hungry autocrat.
Morales, whose campaign slogan is "Secure Future," has fanned fears that Mesa would seek support from the International Monetary Fund, and warned about recent unrest in Ecuador and Argentina over unpopular loan deals with the IMF.
On the eve of the vote, Morales traveled to his rural political base in the coca-growing region of Cochabamba, where he took selfies with supporters and will cast his ballot.
Whoever wins will likely have to govern without a majority in Congress and with a gloomier outlook, as the commodities-fueled boom that has driven rapid economic growth in Bolivia in recent years has ended and the country's key natural gas reserves have dwindled.
Judith Quisbert, a 39-year-old business administrator in the capital La Paz, where Mesa will vote, said she was voting for the opposition as she felt the current administration was beset by cronyism and corruption. "We long for change," she said.
(Reporting by Daniel Ramos in La Paz, Additional Reporting by Ueslei Marcelino in Cochabamba, Writing By Mitra Taj, Editing by Adam Jourdan and Rosalba O'Brien)