Uruguayans vote on Sunday in a presidential election with the ruling leftist party trying to fend off a young center-right challenger who promises to undo a pioneering marijuana law.
Outgoing President Jose Mujica, a 79-year-old former guerrilla, is seeking to hand power back to his predecessor Tabare Vazquez.
Between them, Mujica and the 74-year-old Vazquez have delivered a decade of strong economic growth while Mujica legalized abortion, gay marriage and the production, distribution and sale of marijuana.
Six months ago, the left-wing Broad Front ruling coalition looked a comfortable favorite to win the presidency for a third five-year term for its blend of pro-market economic policies and social welfare measures.
But after an unexpected win in the National Party's primaries, Luis Lacalle Pou, 41, has climbed steadily in polls, tapping into a simmering discontent felt by many Uruguayans toward the far-reaching liberal reforms.
Opinion polls show Vazquez winning 43-46 percent of votes to 31-33 percent for his younger rival. But that would leave Vazquez short of the 50 percent he needs for a first-round victory and facing Lacalle Pou in a nerve-wracking runoff in late November.
Polls show them polling neck-and-neck in the expected second round.
"I don't want the Broad Front anymore," said 85-year-old pensioner Azur Blanco. "They squandered money on the poor, giving them the fish instead of the fishing rod. I also don't agree with the laws on abortion, marijuana or gay marriage."
Lacalle Pou told Reuters on Wednesday he would try to repeal the state-regulated production and sale of weed if he won.
Lacalle Pou's supporters say the surfing enthusiast brings a fresh face to Uruguayan politics with his broad smile and a preference for an open collar over tie. His campaign has rolled out slickly produced campaign ads in the style of Latino pop videos and courted social media.
While financial markets deem the Broad Front's economic policies to be sound, some analysts say Lacalle Pou is more likely to rein in an above-target fiscal deficit and an inflation rate almost in double digits.
But on the streets of the laid-back capital, Montevideo, the Broad Front can still count on strong support a decade after it cruised to power for the first time.
Uruguay's $55 billion economy has grown an average 5.7 percent annually since 2005. The government forecasts lower growth of 3 percent this year, although that is still better than neighboring giants Argentina and Brazil.
The number of Uruguayans living in poverty has fallen sharply to 11 percent from more than a third in 2006. Vazquez has said that if he wins, his government will remain focused on improving conditions for the most vulnerable.
"I vote for continuity, with Tabare, who is a politician with experience, a centrist who does not forget the poor and managed to lift up the country when we were doing badly," said salesman Amilcar Paz, 48.
Uruguay's constitution does not allow a president two consecutive terms in office.
Polling stations open at 8 a.m. (1000 GMT) and close at 7.30 p.m. Exit polls will be released at 8.30 p.m. and partial results are expected by 10 p.m.
Voters also elect lawmakers on Sunday. Neither the Broad Front nor the National Party are likely to win a majority in Congress, meaning the next president will face a tougher time than Mujica in passing laws.
