In a first-round election Oct. 27, Uruguayans split their votes across four parties, failing to give any one presidential candidate an absolute majority. Voters now face a second-round election Sunday.

The runoff will play out in an increasingly unstable regional context, after months of protest and conflict in Bolivia, Ecuador and Chile. Here are four things to know.

1. The Oct. 27 election tested voters’ enthusiasm for the Broad Front.

Sunday’s runoff will see Daniel Martínez of the leftist Broad Front face off against Luis Lacalle Pou of the center-right National Party. Martínez won the first round with 39.02 percent of the vote, followed by Lacalle Pou’s 28.62 percent. The Broad Front has won Uruguay’s past three presidential contests, but it might not be able to pull off a fourth win.

The first-round results suggest an uphill battle for the Broad Front. Ernesto Talvi, the Colorado Party presidential candidate, and Guido Manini Ríos, Open Town Hall’s candidate, were quick to throw their support behind Lacalle Pou — as did the leaders of two other minor parties. If voters follow their lead, the National Party candidate would be on track to victory in the runoff.

The Colorado Party came in third with 12.32 percent. The big surprise? Open Town Hall — a far-right party led by a former army general — won 10.88 percent of the vote. Analysts did not expect to see such a strong performance by an outsider party, given Uruguay’s highly institutionalized politics.

The Colorado and National parties are the country’s oldest. Uruguay’s 2002 financial crisis hit the Colorado Party hard, as President Jorge Batlle had to freeze bank accounts and accept an emergency bailout. Austerity policies saw the economy contract by 6.2 percent, while unemployment shot up and poverty soared. Since 2004, the National Party has been the main opposition party to the Broad Front.

2. The Oct. 27 election also shook up Uruguay’s parliament.

The Broad Front won just 42 of 99 lower-house seats. The opposition (National, Colorado, Open Town Hall, Independent and People’s Party) claimed 56 seats, an outright majority. The left party lost its majority in the Senate, as well. With the exception of one year, the Broad Front has controlled both chambers of Congress since 2005.

Uruguay’s opposition parties appear to have formed a legislative coalition, but the partnership will be fragile because of important ideological differences. That may provide some protection to the Broad Front’s signature policy reforms.

3. The Broad Front saw a number of successes once in office.

The Broad Front emerged in 1971, bringing together the Communist, Socialist and Christian Democratic parties, as well as left factions of traditional parties and independents. But the party did not win the presidency until 2004 — part of Latin America’s “pink tide” turn toward the left in the early 2000s.

The Broad Front maintained unity and saw economic, social and political gains during its three terms in office. Poverty rates dropped from 24.2 percent in 2006 to 5.2 percent in 2017. The party fostered strong ties with social organizations and demonstrated an impressive capacity to mobilize the population using an institutionalized and powerful grass-roots structure.

The focus on mobilizing allowed the party to push for more progressive social policy changes than other left-leaning governments in Latin America. The three administrations expanded social rights in the areas of health care, social welfare, and child- and elder-care policies.

The party also pushed through marriage-equality reforms and measures to legalize abortion and the use of cannabis. Outside of Cuba, Uruguay’s reproductive rights legislation is the most progressive in Latin America.

Where the party was less effective, perhaps, was in responding to citizen concerns about crime and violence. Homicides rose 46 percent from 2017 to 2018, a departure from historical trends. Opposition parties were quick to frame rising crime as a failure by the Broad Front.

4. What does Uruguay’s elections suggest about broader politics in Latin America?

Scholars have studied the nature of Latin America’s left parties extensively. Some identify a radical and moderate strand. Bolivia and Venezuela are examples of the radical group; the Broad Front, Brazil’s Workers’ Party and Chile’s Socialist Party represent the “moderate left.” Other research notes important differences within the two categories. Current political dynamics in Brazil and Chile suggest that the Broad Front is different from other “moderate left” parties.

Far-right candidate Jair Bolsonaro won Brazil’s 2018 election. Bolsonaro’s campaign responded to citizen discontent over corruption, public security and economic decline. His election revealed a weakened left and a political system that had lost legitimacy in the eyes of many voters.

More recently in Chile, protests have threatened the right-wing government of President Sebastián Piñera. Protesters point to inequality and unmet social demands, which governments of both the center-left and center-right have largely ignored. The crisis has exposed widespread lack of trust in Chile’s parties and political institutions, which has limited the ability of the government to respond to protester demands.

Uruguay has avoided such conflict — voters appear generally satisfied with democracy and the overall political system. The Broad Front’s strong connection to social movements and redistributive policies have made it effective at responding to citizen concerns — and avoiding the kind of frustration that appears to be fueling discontent elsewhere in Latin America.

Still, the results of Uruguay’s first-round elections suggest that many voters are ready for change. If the Broad Front loses Sunday, the party will remain Uruguay’s largest political force, controlling roughly 40 percent of the vote and demonstrating strong mobilizing capacity. In the closing event to the October campaign, the party pulled 200,000 residents into the streets of Montevideo — a city of 1.5 million — for a get-out-the-vote rally. That suggests the Broad Front would be a powerful opposition party.

Jennifer Pribble (@PribbleJenny) is associate professor of political science at the University of Richmond and author of “Welfare and Party Politics in Latin America” (Cambridge University Press, 2013).

Fernando Rosenblatt (@NandoRosenblatt) is associate professor of political science at Diego Portales University in Chile. He also does research for the Millennium Institute for Foundational Research on Data and is the author of “Party Vibrancy & Democracy in Latin America” (Oxford University Press, 2018) and co-author of “How Party Activism Survives” (Cambridge University Press, 2019).