Chilean soldiers stand guard at a voting station in Santiago on Friday during preparations for Sunday’s presidential election. (Martin Bernetti/AFP/Getty Images)

Married couple Ema Quezada and Ramón Martínez were among the first to set up shop in a small indoor market in Villa la Reina, a working-class suburb on the eastern flank of Santiago in the shadow of the Andes mountains.

That was 45 years ago.

Today, at 74 and 78, they still tend their grocery stall, but out of economic necessity rather than any desire to remain in the labor force into their twilight years. "Ramón's pension just isn't enough," Quezada said. "We have no choice. We just have to carry on working," she sighed. Many of Chile's 3 million seniors are in a similar position.

Quezada doesn't see much hope of things changing as a result of Chile's presidential elections Sunday.

"Don't like any of them," she said of the candidates. "They just look out for themselves, and they're always attacking each other."

Quezada's frustration with the economy and politics appears to be widely shared in this South American country that is often held up as a model of free-market democracy since it voted out its dictator, Augusto Pinochet, in 1988.

In the first round of the elections, held Nov. 19, just 46 percent of the country's eligible voters made their way to the polls. This continued a trend of low turnout noted in last year's municipal elections (34 percent) and the general elections four years ago (49 percent). Chile abandoned compulsory voting for registered voters in 2012.

Sunday's election is a runoff between conservative billionaire Sebastián Piñera, who took nearly 37 percent of the vote in the first round, and center-left candidate Sen. Alejandro Guillier, who won 23 percent. Six other candidates competed in that round.

The big unknown Sunday is what role will be played by a relatively new political force, the Frente Amplio, or Broad Front, a coalition of leftist parties and social organizations demanding major political and economic reforms.

Led by Beatriz Sánchez, who against all polling predictions received 20 percent of the vote in the first round of the presidential elections, the Broad Front expanded its presence in the 155-seat lower house from three seats to 20 and picked up its first senator in the upper house.

While Sánchez did not qualify for Sunday's runoff, she has endorsed Guillier. Her supporters could put the center-left candidate over the top in what would be seen as a major upset. But it is unclear whether those voters will turn out en masse to vote for a man seen as a cautious reformer.

Chile has boasted one of Latin America's fastest-growing economies in the past few decades, and the country has been politically stable with little corruption. But while the World Bank considers Chile a high-income country, it is also highly unequal.

What that means to many ordinary Chileans is that wages and pensions are low, living expenses high, and basic public services — particularly health care and education — of poor quality. Adding to voters' concerns, economic growth has been sluggish in recent years because of a drop in prices for copper, a major export.

Citizens' responses to these problems have been not voting or shifting to a different party.

The Broad Front traces its roots to student protests in 2006 and 2011 that sought the improvement of the public education system and social and health programs, as well as a new, more democratic constitution.

In Chile, official statistics put the poverty rate at 11.7 percent, or 2 million of the country's 18 million people, with 3 percent of the population suffering extreme poverty. But critics say that the numbers are based on a shopping basket from the 1980s and that the true poverty rate is much higher.

Both candidates in Sunday's runoff embrace Chile's free-market system. Piñera, who served as president from 2010 to 2014, has pledged to double economic growth, create hundreds of thousands of jobs and streamline the tax code. Guillier, a former TV news anchor, is promising to tackle inequality through reforms to education and labor policies, and to hold a plebiscite to replace the dictatorship-era constitution. The current president, Michelle Bachelet, who belongs to Guillier's center-left coalition, is ineligible to seek immediate reelection.

Economist Marco Kremerman, who works at the Sol Foundation, a left-leaning think tank, said Chile has a serious wage problem. The minimum wage is set low, at the equivalent of just $417 a month, which "has no relation to the cost of living," he added.

He noted that many economic regulations were written under the dictatorship and that labor laws are weak.

"Workers don't have any negotiating power. In Chile, less than 15 percent of the workforce belongs to a union, and secondly, less than 10 percent have access to collective bargaining," Kremerman said, referring to a legally binding forum for negotiations between employees and employers.

In the capital's "Sanhattan" business district, however, the view is very different. Industrialist Bernardo Larraín Matte, president of Sofofa, Chile's manufacturers association, countered that higher wages will come with increased productivity.

He noted that the country's larger corporations in the mining, forestry, agricultural, retail and financial services sectors have generally higher wages and productivity, while smaller and medium-size businesses are inefficient and so pay less.

He said employees should be free to negotiate directly with their employers and not just through a union or collective bargaining.

"If you look at the large corporations that are dominant in the global economy, unionization really isn't an issue," he said, mentioning Airbnb and Uber as prominent examples.

He singled out the Chilean retail store chain Falabella as particularly successful. Indeed, at one Falabella store in Santiago, a floor assistant, who identified herself only as Mónica, said her minimum wage is supplemented by productivity bonuses, giving her a comfortable $780 monthly take-home pay.

"Management treats us well, and the bosses always give you a hug when they come down to the shop floor," she said.

She admitted, however, that without her husband's income, her paycheck wouldn't be enough to live on. Falabella's workers also all belong to a union.