Colombians are voting Sunday for a new president who will face sharp challenges: hundreds of thousands of hungry Venezuelans pouring into the country, the unravelling of a peace accord that ended a 50-year civil war, soaring cocaine production and a stumbling economy.

Five candidates are in contention, but the two likeliest to move to a June runoff are the ones Wall Street most loves, and the one it most fears, amid increasing polarization in the country of 50 million.

Ivan Duque, a protege of former President Alvaro Uribe, and an advocate of cutting corporate taxes and a backer of Big Oil, had 42-per-cent support in the most recent poll released May 20th. He was followed by 30 per cent for Gustavo Petro, a former guerrilla and mayor of Bogota who wants to reduce the country’s dependence on hydrocarbons, redistribute land and develop new export markets such as avocados.

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“Colombia’s economic model is under discussion,” said Munir Jalil, Citibank’s chief economist for the Andean region. “Gustavo Petro wants to finds substitutes for oil and coal, while Duque just wants to complement them with other exports.”

Polling stations opened at 8 a.m. and close at 4 p.m. local time, with results expected early evening. If none of the candidates gets a majority, there’ll be a run-off vote on June 17.

Ecopetrol shares

Mr. Duque, 41, campaigned against the 2016 peace accord with Marxist rebels, saying it was too lenient to those with blood on their hands. He’s expected to do what he can to dismantle it while Mr. Petro, 58, backs the deal.

The other contenders are considered more centrist and include Sergio Fajardo, a former math professor and mayor of Medellin, and German Vargas Lleras, who has a strong party machinery getting the vote out for him, even though the most recent poll only gave him 7-per-cent support.

“You’ll see the market get nervous if Petro reaches 30 per cent or more of the vote in the first round,” said Carlos Enrique Rodriguez, director of equity research at Ultraserfinco in Bogota. If this happened, the peso would weaken and the stock market would drop, he said.

Ecopetrol, the state-controlled oil company that Mr. Petro has said he would like to convert into a solar power company, would probably see its shares drop, he added. At the same time, if Mr. Duque wins outright in the first round, or if Mr. Petro fails to make the second round, many analysts expect to see a rally in Colombian assets.

Weak economy

Last year the economy grew at its weakest pace since the global financial crisis, as consumer confidence slumped and the government’s highway-building program stalled following a corruption scandal.

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The government’s peace process with the Revolutionary Armed Forces of Colombia, or FARC, has also run into trouble. The guerrillas handed over their weapons last year, and relaunched themselves as a legal political party, but the areas they abandoned were swiftly taken over by drug-trafficking gangs, and dissident FARC members disaffected with the peace process.

Production of coca, the raw material for making cocaine, more than tripled between 2012 and 2016, fuelling violence in the countryside where it is grown.

Whoever wins, and takes office in August, will also need to deal with the implications for Colombia of the collapse of the Venezuelan economy. It has created the biggest migration crisis in Colombia’s history, as hundreds of thousands cross the border each month, straining public services such as health care and schooling.